okay here the text for the crash i mention earlier
Praise God! My fierce rival has also become a follower of the new way of Christ! Hallelujah!
Highlight I need to re-evaluate our relations! <- CTD
Love thy rival does not apply in this situation <- game goes on as normal.
And that option causes an immediate crash?
That's odd. All it does is send an event back to the person who sent it to you. I just tested it out in-game, and it worked just fine (though I had to fire this manually -- normally this is caused by a rival of a different religion converting to your own).
Assuming you have the correct checksum, all I could suggest is that you send me a save where this is occurring and I'll check it out.