A quick scan of any STEM careers fair confirms that which we see in headlines: war is big business. For many generations, the defence sector has been one of the primary employers of STEM graduates and this trend looks set to continue. Close to a third of my university cohort now work for arms manufacturers with many others doing PhDs sponsored by such companies.
Can we, as Christians, work in the arms industry? How does this reconcile with commitment to obeying Jesus?
In order to answer this question, we will discuss two further questions, the results of which should inform our thinking on the primary one.
The first of these is, “How does working in the industry relate to using the weapon?” Very few (if any) Christians would argue that the design of an aerodynamic nose cone is inherently sinful. Matters of morality become vastly more complex when the nose cone is mounted on a Hellfire missile.
Secondly, we will look at whether it is right for the operator to use arms, or to formulate the question in a different way: “When, if ever, is war the right thing to pursue?”. This is a question that has been discussed throughout the ages. I don’t have the wisdom to provide a novel answer to this question; instead we will leverage biblical principles developed by a series of heavyweight Christian thinkers.
The aim of this article is to provide a set of principles that relate the STEM worker to the military action and then determine whether or not the military action is right. By doing this we should be equipped with a set of questions to ask about the morality of a specific role in the arms industry.
A quick word on who I am in relation to this topic. I’m an engineer by training and my master’s dissertation focussed on military unmanned aerial vehicle (UAV) design. Having had experience working on technical projects for prime defence contractors, I now work as a consultant in the Aerospace and Defence sector. As I tell my mum: I’m not an arms dealer; I just advise arms dealers. I’m also a Christian.
My answer to this question has changed more than a few times over the years, prior to stabilising it via this kind of thought process.
How does working in the industry relate to using the weapon?
The purpose of this section is to see if a STEM graduate working in defence has any moral responsibility (either positive or negative) for the actions committed with the tech they’ve created. If there is no moral culpability then there is no reason why Christians shouldn’t work in the arms industry. However if there is (as we shall see is the case), then understanding how we might be held responsible for this in the courtroom of heaven (see 2 Corinthians 5:10) will be helpful in answering our original question of whether Christians can work in the arms industry.
The general principle
The Bible is clear that we are responsible for our own actions. Ezekiel 18:20 plainly shows us: ‘The soul who sins shall die. The son shall not suffer for the iniquity of the father, nor the father suffer for the iniquity of the son. The righteousness of the righteous shall be upon himself, and the wickedness of the wicked shall be upon himself.’ (ESV). We see this idea in other places in Scripture (e.g. Isaiah 3:10-11 and Galatians 6:7-8). As humans, we are given the ability to act according to our desires and one day we will be required to give account of all our actions before God (Romans 14:12).
But those who work as researchers or engineers aren’t actually firing the weapon - so to what extent is it their action?
In order to design any useful product, you have to have some idea of what the use is going to be. As such, an engineer who designs product X for specific use Y can be held responsible (in a biblical sense) for the use of X to do Y because they act towards that. It hopefully shouldn’t be controversial to say this: if you know your product is going to be used for something particular, then you are - to some degree - responsible for that.
The specific application
So how does this influence our thinking for the defence industry? There are two broad considerations to be made: one technical, one tactical.
Technical considerations are usually simpler. They revolve around a question like: How will this technology behave if it is deployed in a technically correct manner? The answer to this may well be the performance requirements given throughout the project. The designer knows how the technology should perform (assuming they are doing their job well) and as such is responsible, to some degree, for when the device does that thing.
Let me give an example: The EXOCET missile family is a (rather prolific) series of anti-ship missiles. The designers of the EXOCET have designed these products to sink ships, knowing all along that this was how the technology would behave. So while they aren’t responsible for pressing the FIRE button, they nonetheless act towards certain ships being sunk and are therefore responsible, in some part, for the sinking of these ships. Why? Because they designed missiles specifically for that purpose. All this is to say, you are responsible for what the product physically does, if you made it to do that thing.
Tactical considerations, however, are far more complex. This is less a question of knowing what your creation does and more a question of knowing who you are selling it to and how they will use it. Knowing this isn’t simple, as you may not know who the exact customer is, or the ins and outs of their methods.
However, in the cases where the customer and their concept of operations is known, the designer in question acts towards that end and as such can be held partially responsible. By way of example, General Atomics knows that whenever they sell an MQ-9 Reaper to the US Air Force, it’s used 95% of the time for counter-insurgency hunter-killer missions in the Middle East. As such, they are partially responsible for the facilitation of hunter-killer missions in the Middle East against insurgents. What General Atomics are unlikely to be responsible for is what happened when the MQ-9 interacted with Russian jets over the Black Sea  as that was a fringe case, unforeseeable by those who designed it.
One practical way of finding out who is using what is simply looking up the plane/tank/missile on Google news. Defence news outlets do a pretty good job of tracking the distribution of major products.
This is to say that if a weapon is used in the designed manner for a known application, the facilitator of this (i.e. the STEM graduate) is partially responsible. For these known cases, the moral responsibility of the facilitator is tied in with the moral responsibility of the operator.
Ascertaining the morality of this operator, then, is the next task in answering our question.
When is war, if ever, the right thing to pursue?
We’ve seen that if an engineer designs equipment, knowing it will be used in a certain way, they are responsible for that. Now we will discuss principles to determine whether the use is right or wrong.
Is war ever right?
There have been gallons of ink spilled in answering this question. Our discussion will be very brief. For fuller treatments, read ‘War, Peace, and Violence: Four Christian Views’ ed. Copan. 
The call for Christian pacifism is historically couched in Bible passages emphasising forgiveness, love and loving our enemies  - none more so than Matthew 5:39-44 , in which the Lord Jesus calls for a turning of the other cheek and the loving of our enemies. It’s plain to see how a call for pacifism follows from this.
The majority evangelical understanding is that this doesn’t prohibit war. One of the key passages to answer this has been Romans 13:3-4:
‘For rulers are not a terror to good conduct, but to bad. Would you have no fear of the one who is in authority? Then do what is good, and you will receive his approval, for he is God’s servant for your good. But if you do wrong, be afraid, for he does not bear the sword in vain. For he is the servant of God, an avenger who carries out God’s wrath on the wrongdoer.’ (ESV)
In this we see that governments are granted the right, by God, to use the sword to restrain evil and punish wrongdoing. That they actually ‘serve’ God by carrying out wrath on the wrongdoer.
This same teaching is later reiterated in 1 Peter 2:13-14:
‘Be subject for the Lord’s sake to every human institution, whether it be to the emperor as supreme, or to governors as sent by him to punish those who do evil and to praise those who do good.’ (ESV)
Throughout the ages this has been understood by Christians (including Augustine, Aquinas and Calvin - more from them in a moment) as justification for proper authorities waging ‘just war’ in order that evil might be prevented rather than propagated.
Various other passages are often quoted to support this argument - among them: Luke 3:14 (John the Baptist doesn’t condemn soldiers for being soldiers), Ecclesiastes 3:8 (acknowledging there is a time for war), and Matthew 8:5-13 (where Jesus doesn’t condemn the centurion).
This ‘just war’ ultimately takes its cue from God’s means of bringing about justice. While we’d want to highlight significant differences with how God works now, in the Old Testament God frequently used war to bring about justice (Genesis 15:16; Numbers 21:3; 31:1–7; 32:20–21; Deuteronomy 7:1–2; 20:16-17; Joshua 6:20–21; 8:1–8; 10:29–32; 11:7–20; 1 Samuel 15).
We no longer live in a theocratic state like Old Testament Israel, but rather see this concept continued in God’s common grace  as he puts authorities over us to “punish those who are evil” (1 Peter 2:14) and as “an avenger who carries out God’s wrath on the wrongdoer” (Romans 13:4). As such, most evangelicals agree that the Bible teaches that ‘just war’ is allowed (and perhaps even encouraged). 
The big question now is what defines a ‘just war’ - and it’s to that matter we now turn.
Just War Theory
We will now look at seven principles which determine whether a war is ‘just’. These find their origin in ideas formulated by early church father Augustine,  and later formalised and expanded by a variety of Christian scholars. The first five concern the justice of going to war; the last two the justice of what is done in war.
Given that I’m no expert in military law, weapons technology, or battlefield tactics, I will stay far away from attempting to designate specific conflicts or practices as either just or unjust. Instead I’ll briefly explain each principle and pose a question each of us can ask ourselves as we seek to honour God in the decision to work (or not work) in a role within the arms industry:
1. Governmental authority - war must be carried out by official governments.  This is directly derived from the Romans 13 passage we saw earlier. It’s not the place of individuals or corporations to declare war but rather, as Augustine tells us, “the power to declare and counsel war should be in the hands of those who hold the supreme authority”.  Of course this doesn’t legitimise any act of war carried out by a government, only those which fall under the purview of Romans 13 (which the rest of the principles outline).
Will the technology be used by official governments?
2. Just cause - war is in response to wrongdoing. As Aquinas puts it: “those who are attacked, should be attacked because they deserve it on account of some fault.” . Romans 13:4 again is pertinent here. A government may go against a wrongdoer.
Will the technology be used against those who ‘refus[e] to make amends for the wrongs inflicted by its subjects, or to restore what it has seized unjustly’? 
3. Rightful intention - the only just intention of war is the bringing about of peace. Peace (shalom) is one of the primary purposes of any just war or judgement in the Bible.  In war, government’s ‘sole endeavour should be to provide for the common safety and peace of all’.  As we are all aware, it’s very much possible to go to war with just cause but ill intention.
Is this war being waged to bring about peace?
4. Last resort – war should not be rushed into hastily, but be reserved for when diplomatic solutions have been shown to be impossible.
Have all other attempts for peace failed?
5. Limited ends - only to restore peace, repel attackers and punish injustice; not to expand kingdoms or colonise. 
Is this war seeking to do more than solely restrain and punish injustice?
6. Proportional - response should be proportional to the infraction. If one nation sinks another’s frigate, they shouldn’t respond with nukes.
Is the operation of this weapon likely to be a proportional response?
7. Discrimination - noncombatants should never be targeted and should be actively avoided. If the person isn’t a ‘wrongdoer’ who disturbs the peace, there is no right for the government to kill that person.
Is this method of warfare making every reasonable effort to avoid civilians?
If, having asked ourselves these questions, we come to the conclusion that the known uses of our tech will be just, then (to my mind) there is no reason why you shouldn’t work in that specific role. If, however, it becomes apparent that a specific role will require you to work on tech when you know the use will be unjust and not in line with the mandates of Romans 13 and 1 Peter 2, then it’s likely that as a child of God, you shouldn’t do that role.
As with many biblical principles, applying them is easier said than done. It won’t always be clear exactly what a role will involve or how the tech will be used. But as we carefully and prayerfully consider, we are guaranteed a helping hand: ‘If any of you lacks wisdom, let him ask God, who gives generously to all without reproach, and it will be given him.’ (James 1:5)
One of the practical things I’ve found helpful in aiding this process is getting in touch with Christians at the company and asking how they find the work (HR will usually be happy to put you in contact with the Christian group in that workplace). They may not agree with you on everything, but they will be able to help clarify the nature of the work.
Another thing that might help you be more objective is to think about this before you apply, suffer through the interview or get an offer for a particular defence role. I find that my principles can mysteriously evaporate once I get invested in an application.
My own personal conclusions have led me away from working for defence contractors but still within the industry. However there are many Christians I respect (and who are far wiser than me) who do work for the companies I wouldn’t join. The aim is not to persuade you into or out of a particular job but rather - God willing - to suggest some principles that help you to navigate this question. Regardless of your position, you shouldn’t go against your conscience, though it is important to check that your conscience is biblically informed. 
The final thing to say is that even if we answer this question with an emphatic yes, our ultimate security is not in these things. ‘Some trust in chariots and some in horses, but we trust in the name of the LORD our God.’ (Psalm 20:7). In fact, Christians in the arms industry should long for the day when their handiwork is broken; at the second coming of Christ all appurtenances of war will be destroyed (Psalm 46:8-11), as the Divine warrior king ushers in an eternal era of peace (Revelation 19:11-20:10). Let us be people who long for and pray for that day!
 Capturing and quantifying the contribution of the defence sector to the UK economy, Joint Economic Data Hub, Annual Report 2023, May 2023 https://jedhub.org/docs/2023/20230504_JEDHub_Annual_Economic_Report_2023_v1.0.pdf
 Copan, P. (Ed.). (2022). War, Peace, and Violence: Four Christian Views. InterVarsity Press.
 Macgregor, G. H. C. (1936). The New Testament Basis of Pacifism. Fellowship of Reconciliation.
 Palmer, H. (2016). Christian Pacifism and Just War Theory: Discipleship and the Ethics of War, Violence and the Use of Force (Vol. 2). TellerBooks.
 Carson, Just War, https://www.thegospelcoalition.org/sermon/just-war/
 Bavinck, H. (2011). Reformed dogmatics: Abridged in one volume. Baker Academic. p159
 Clouse, R. G. (n.d.). War--4 Christian Views. IVP Books.
 Langan, J. (1984). The Elements of St. Augustine’s Just War Theory. The Journal of Religious Ethics, 12(1), 19–38. http://www.jstor.org/stable/40014967
 From Constantine to Calvin: The Doctrine of the Just War’, in C. Villa-Vincenzio (ed), Theology and Violence: The South African Debate (Erdmans: Grand Rapids, 1988).
 https://www.thinkingfaith.org/articles/20131011_2.htm#_edn6 - accessed 27/12/23
 Augustine, Contra Faust. xxii, 75
 Aquinas, Summa Theologiae, Second Part of the Second Part, Question 40, Article 1
 Augustine, QQ. in Hept., qu. x, super Jos.
 https://www.christianity.org.uk/article/war-and-peace - accessed 29/12/23
 Calvin, Institutes IV.20.9.
 Carson, Just War, https://www.thegospelcoalition.org/sermon/just-war/ - accessed 27/3/23
https://www.desiringgod.org/articles/dont-always-follow-your-conscience - accessed 29/12/23
Enjoyed this article? You might like these other resources on a similar topic: