You have no need to explain that to them.
But I do have the desire.
I was gonna make a thread asking if it's better to be honest with my family about my gayness and spirituality, or if I should act like a straight Christian for the rest of my life in their presence. It seems I can get the desired input from this thread though so I'm asking here.
If I want to be able to be open about my thoughts and express myself freely with my family, then I do think I have the need to explain to them.
My dad always complains that my older brother is gay. Tells me "at least you came out straight". I think my dad would be happier if he never knew I was gay. To illustrate his thinking... He tells his mom (my grandma who lives far away) that I'm still happily married to my first wife. He explains to me that it's better to tell her that to not stress her out. So maybe I should apply my dad's own logic to him.
My other grandma from my ma's side and my ma's sister are super Christian and I've been pretty committed to acting like I'm Christian for the past while. But I'm at least as spiritual as them (they being very spiritual)... I'm just not Christian like them. But I would like to be myself with my family. I just don't want grandma in particular to believe I'm gonna burn into a crisp for all of eternity. But does that matter? If I want to be open, should I be open? It's either be myself and honest with them or keep up the charade for the rest of my life. I think I'm beginning to see the better option.
Why explain yourself? It's your religion not theirs.