Do you come from a Christian background?

No, but I have seen a lot of different mental interventions. There are a lot of different ways to get to certain effects. Effects feel only special if you know just one way to get to the effect. I have seen people cry because of the beauty of life without them being on drugs or any religion being involved.

Believing that one is loved is certainly useful but the core belief is not "I'm loved by God" but the generalized "I'm loved". Children learn "I'm loved" or "I'm not loved" when they are very little based on the experiences with their parents. As they grow older they then apply that belief in multiple situations. A Christian will feel deeply loved by God or he might be afraid of God.

If you deeply feel loved by God you shouldn't have a problem to feel deeply loved by your friends because it's the same core belief. You still have the same fun with your old Christian friends and family and feel that they are understanding where you are coming from.

Your belief might in "I'm loved" might be a bit shaken, but I think the core will still be intact.