Nehemiah 4:9 And we prayed to our God and set a guard as a protection against them day and night. (ESV)
In addition, there a few actions that can be taken even when Christians heed Paul's exhortation not take revenge but to leave vengeance to God (Romans 12:19).
For a start, not taking revenge doesn't mean gong-gong let people slap nor maximising the areas where others can slap. It does mean, as in Nehemiah's case, taking self-defense measures. He "set a guard as a protection against them".
Believers live in the world but do not have jurisdiction nor muscular power nor power of any sorts in that same world. Throughout history, the believers' influence in the world rise and fall. But there is that additional padding that believers can utilise to cushion hurt to self from unwanted and unwarranted sources.
In planning, you and I might just have to plan in such a way to minimise hurt in case others fail us, or attack us, or kena sabo. It is not something that feels meaningful nor enjoyable. But what to do? We live in a fallen world, fallen humanity, including ourselves.
Pray to God because we need help and recognise He is LORD. We can also pray for the opponent and their salvation because The LORD ultimately wishes for all of creation to find fulfilment of their created purposes and also find salvation in Him (Ezekiel 18:23, 23. 2Peter 3:9).