Bruce Charlton explains:
But Christians are equipped with the infinite power of repentance; which means that no matter how many times we are ‘broken’, no matter how may times we are defeated and unconditionally surrender to evil – or actively support and promote evil. We can and should simply repent our sin, we will be forgiven, and we start over again: fighting and resisting.
The point is not so much winning, as not being defeated; and the point is not so much not being defeated in our bodies and actions, but not being defeated in our souls.
A Christian should be indomitable, and all Christians are able to be indomitable – perhaps most of all those who are weakest and least likely to suppose that they can win by worldly power.