That's just false. Look up on Kikepedia. It's the Romans that brought Christianity in Europe. And that's why they became too cucked to fight back against the Germanic tribes.
Why do you think the world capital of Christianity is Rome and not Berlin?
You're also not really understanding the historical context. The concept of nation state didn't exist back then. The Roman army had people from everywhere, including a ton of Germanic mercenaries. It also ruled in territories that were populated by people of Germanic blood, like northern France, from which it took its soldiers. It wasn't an homogeneous nation, it was a multicultural empire. So I'm not sure what point you're trying to make.
The Germanic tribes that overthrew the corrupt Roman Empire were almost all fully converted by the time they did so.
Conversion first, victory second.
Why do you think the world capital of Christianity is Rome and not Berlin?
You're also not really understanding the historical context. The concept of nation state didn't exist back then. The Roman army had people from everywhere, including a ton of Germanic mercenaries. It also ruled in territories that were populated by people of Germanic blood, like northern France, from which it took its soldiers. It wasn't an homogeneous nation, it was a multicultural empire. So I'm not sure what point you're trying to make.