This is a response to Michael Bird’s post. Comments there are restricted to paid subscribers, this is why my response is here and not there.
I find this post just a little disingenuous.
Firstly, Bird well know that there are Christian Pacifists still out there. Perhaps not as prominent in some previous eras, but they certainly exist and are doing theological and practical world in the world.
Secondly, there are varieties of Christian pacifism and I wouldn't presume to speak for all of them, but I think a few points can be made in response to his post.
Yes, by classical Just War criteria, the Ukrainian position in the Ukraine war is a Just one. That certainly ought to make us much more sympathetic to Ukraine in this conflict. There is a strain of pacifism which we could call "Just War pacifism" insofar it thinks a Just War would be a permissible thing, but no war has ever met that criteria. Most wars do not, let's be honest. Ukraine, from what we currently know, seems to fit the bill pretty well. But most forms of pacifism are not predicated upon whether those criteria are met or not, nor is pacifism ultimately about "workability"; pacifism is rarely driven by the belief that it is likely to create better outcomes.
Christian pacifism is more generally rooted in a few points: firstly, that Jesus taught a form of non-violent resistance in which killing our enemies is not (or no longer) a moral option for believers. It's not an option on the table. Secondly, that Jesus is paradigmatic for this form of non-violent resistance. Thirdly, that we ought to actively resist evil, love our enemies, pray for persecutors, and desire the defeat of violent and wicked people, but not by the means of killing them.
I dare say, it is consistent with Christian pacifism to think that (a) Russia is an unjustified and immoral aggressor in this conflict and to pray that God will deprive them of the ability to inflict harm; that (b) Ukraine as a state and nation is engaged in legitimate self-defence, and we may hope and pray for their victory in this conflict, (c) still think that Christians are obliged not to engage in military action or acts of violence.
None of this comes to bear on the questions of diplomacy and politics, which is where he seems to be driving towards the end of his post. Pacifism says much more about how believers and the church should act, far less about how governments and nations ought to conduct themselves. A principled commitment to pacifism in relation to the Ukraine is unlikely to think the political solution was or is appeasement of Russia, but creative, sustained commitment to non-violent resistance that has surrendered the option of killing. It also involves a heightened commitment to God's sovereignty, in which we are not ultimately responsible for defeating evil empires, but we know one who can and will. As for us, it would be better to die as witnesses to Jesus' command to love our enemies, than to kill them to save ourselves or even our neighbours.