Hello, I am Rafael. Thanks for asking your question - I'm here to support you. (Information posted here is not private or confidential but public).
I am sorry to know about this challenging situation.
You are totally right when you say religion is a big issue, since for relationships to develop and grow as healthy and truly fulfilling ones, both partners need to share the same value and belief systems, otherwise constant destructive conflict or disagreement would arise leading to the need of relationships, or to thier perpetuation as dysfunctional or unfulfilling ones.
People could have great qualities but they never guaranty happiness and fulfillment in relationship, what could only be developed by team work between two people sharing compatible personalities, having mutual interest, core needs and expectations in life, and same values and beliefs, since it is from here that we shape everything we do in life.
Grief is natural and necessary experience in life for people to mature and grow as whole human being. It allows as to mature and value things and what truly matters. Your role is to guide, model what is assertive and support in respectful and empathic ways your son, with unconditional love and consistent and assertive discipline and good judgment. Please continue to support him the best you can.
Thank you for your trust.