When I was a Christian, I met many people who siad they had a hope in things that I, as a Christian, considered to be wrong. Having learned from scientific studies that the basis of their hope often had more to do with their identification with caring individuals in a community, rather than due to the specifics of their religion
This is a non-sequitur, and a breach in logic. Science cannot do what you are crediting it with here. but now what you're saying isn't debate, while what
I'm saying is - oh the irony!
I think part of the stigma we're having over "debate" here is just the usage of the word.
I thought it would be good for them to understand that it might not be the specifics of their religion that was making them happy, but rather, the feeling of community.
False dichotomy. Christianity IS relationships. Primarily w/ the Father, yes; but not in a vacuum. Other believers are absolutely essential for this to take place. Therefore what you're referring to as a mere "feeling," is actually much MUCH more than just that, within true Biblical Christianity. And the associated feelings are also holy

(See my tagline quoting Harry)
how did I know that it wasn't just the community of believers that was making my happy?
Happiness to be found in Christianity IS largely attributable to the community of believers, so here you merely developed the above false dichotomy further. Likewise we are also to share one another's sorrows, and bear one another's burdens.
Understanding a few terms might short-cut your learning process to see what you were missing in your perception:
koinonia (translated many ways, perhaps including fellowship?)
Eucharist - also translated various ways, but I think easier to track down.
Do you know how to use blue letter Bible? I hear E-sword is even better. Makes all my hard copy resources obsolete!