My grandpa doesn't go to church and is not saved. What verses do I need to tell him out of the Bible.
This is a question I would love to be able to answer but cannot. I don't know your grandpa. I don't know why he has decided against being a Christian. Because of that, I don't know where to start to change his mind. But, you know things that I don't; you know who you are dealing with.
There isn't a magic formula that convinces everyone to serve God. It takes different reasons for each person. Take a look at the book of Acts. Every example of conversion started with different topics, and different lines of reasoning to arrive at the single conclusion that you need to be saved.
The best way to help your grandpa is to first listen. Ask him why he never goes to church and then really listen. Think as if you were in his shoes. What would it take to convince you that you needed to change if you were your grandpa. When you come up with something, then make that one single point and see what happens. Don't try to overwhelm him with a flood of reasons. Just make a point and if he doesn't move, then work on another point to make at another time.