Responses
I do think the saint is the ML... It says in chapter 4 that "Rumors swirled that he'd fled immediately before his execution, and became a bandit or found religion and converted"
If he became religious it can certainly explain the change in personality, and besides I feel like the looks match
I really don't think that ML is the Saint bc MC did say he died shortly after he(MC) fled from the war in the past. And the personality just doesn't match.
I don't really know tho, just my personal thought ┐(´∇｀)┌