Hello everyone, I would like to know if there is some sort of trigger when Christianity can appear while building nanban port

To be more specific, I am playing master of strategy mod and while I can build nanban trade ports and Christianity spreads - I cant convert and dont get the message saying you can convert. So I would like to mod it if possible, however I cant find where the trigger or date when it can fire is located. Any help in this matter would be greatly appreciated