Say that you join a "youth social and adventure group", where, while rock-climbing or bowling or hiking, its core members will begin, subtly, to sound out your religious beliefs and talk to you about God, is that at all morally problematic? Or in general, if any group has the main raison d'etre of recruiting for a church/political party/pyramid scheme, but initially conceals this motivation (for instance, through initially avoiding any mention of the parent organisation), is there anything wrong with that?
There is something plainly wrong with a group that conceals its real purpose, surely, and lures you in with a false front. But there is nothing wrong with members of a group that is visibly religious in orientation inviting someone to come along and join. 'Why not come and join our Catholic knitting group?' is fine. As to your first question, being sounded out seems OK, because if it get too intense or probing you can always leave. I do think there is something a bit off about a religious group targeting people who are a little lonely or isolated, but on the other hand if there's no expected quid pro quo where's the harm? The devil is in the details of how things are done, I think. Concealed pyramid schemes are another thing altogether, because here the element is deception is at the centre of what's going on.