Going to heaven is not something we HAVE to do. It is what we are blessed to be able to do thanks thanks to Christ.Tell them to go read their bibles. The book of Romans explains over and over that being a Christian does not require you to do anything. The only thing a Christian has to do is go to heaven.
I can't point to any verse, but AFAIK the only reason to go to a meeting is to fellowship with like-minded believers.
I would say that what we HAVE to do is treat other people in the manner that you want them to treat you. This is a hallmark of Christianity. Be kind to people, even when they are unkind to you. That way, you set an example for them, you become a representative of the Christian faith.
Matthew 7:12 Jesus Himself said......……….
"So in everything, do to others what you would have them do to you" .
Matthew 18:20 ........
"For where two or three gather in my name, there am I with there also". = Fellowship and worship.
"Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching." = Obedience.