My sister in law ends every text in capital letters reading 'god bless you' i ignore until i want to end conversation and then just send a heart. Its annoying, but i pick my battles.

Even liberal Christians often have a red line that considers the absence of some form of belief in some kind of god to be a bridge too far. Just be thankful he's not taking it further than that. My Dad would snarl at me if I forgot to pray before a meal. He needed me to at least play-act the role he'd taught me as a child. He wasn't terribly curious about my character or actual beliefs or motivations so much as my outward conformity. And that is typical of fundamentalists, they are way more interested in being right than in being good. Fortunately your Dad has fairly limited concerns. You could be gay or trans or poor or unemployed or sick and he'd still love you. That's progress.

In fairness to the memory of my father, who I have zero resentment towards and lots of respect for, he managed to mind his own business so long as I didn't do something gauche in his presence, so that was pretty accepting for a fundamentalist. But still ... it was awkward and exhausting living a lie for him. Fortunately for me I lived a couple thousand miles away from him towards the end of his life.

He loves you. Keep smiling.