A few things:
OP, you're not going to find what you're looking for here on Long Island. Most people here keep their faith private. You do have some people who occasionally go to church on Sunday out of tradition, but it's not as common. If you do move up here, I recommend finding a good church, and making friends there. Many of them do have activities for families during the week, and you can build your community of friends there.
To be honest, we don't really have Christian enclaves on Long Island. Most Christians here make their friends at church and other organizations. As an aside, despite how progressive posters on here try to make Long Island seem, there aren't many LGBTQ families here. Minorities already have it rough here, so you can only imagine how gay people would fare in many neighborhoods
Also, Long Island still has a VERY solid Republican presence.
I DO NOT reccomend that megachurch on Route 231 that another poster mentioned (it's called Upper Room World Christian Center). You can DM me, if you want to know why. Some funky stuff appears to be going on there-- it's definitely not the powerhouse it was back in the 90s.
To the other posters, the OP did not ask your opinions on her family's beliefs, she asked where Christian families on Long Island typically live. There was no need to belittle their belief system in the midst of telling her those enclaves don't exist here.
OP, don't let the cynical posters here paint a picture of Long Island at large. Most people here are open minded about things like this unless you try to force feed your beliefs on them. I'm non-denominational, and don't feel threatened because of my beliefs here