Christians who support Israel are just useful idiots for Judaism.
 
I agree.
Modern Christianity is no better than Judaism.  Both are horrible.  Both hate free speech.  This is why I support Islam.
 
Islam doesn't hate free speech?
But I don't have any advice for white nationalists, they seem like a lost cause to me precisely because they don't have a reasonable religion to get behind.
 
Christianity seems like the best option.  Traditional Western Christianity, not modern liberal cuckianity.  Odinism is an interesting alternative.  A new religion could be founded based on Homer's or Tolkien's epos.