The fact of your lack of belief questions such people's beliefs. They are also enjoined to witness that faith.

Severe brainwashing doesn't allow them to think logically. Just ignore the messages you get from this person, or use a block filter and if on social media just block or unfriend.

Christianity is programmed that it’s all true.
It’s their attempt to try and save you.
They are not interested in listening.

I'm so sorry this is being shoved down your throat. I don't understand the reasoning behind it but I'm here in solidarity with you. I was married to my Christian husband for almost seven years and the first 2 he spent trying to convince me there is a god. As you can see it clearly didn't work.