Hi soliek.
This is a big and pervasive problem. The people who have the know-how to help are the exact
ones turning them off. These people have a BIG mechila to ask for having stunted and prohibited the spiritual development of those you are talking about in your post. Maybe they are not totally responsible, but they had an obligation to do a better job to tip the scales favorably rather than in the other direction.
I have run into this kind of thing and learned that sometimes the religion and the people are two different things.
I want to say clearly, that there are people in our community who are worth more than their weight in gold, more so than any other people in the world. They are unbelievably thoughtful, kind, helpful, and knowledgeable. But sadly, a very few are messed up and mess others up.
In my opinion, there is no exact solution that can be laid out like a list of things to do, as you know.
I often tell people who share their disappointments in their religious experience that they cannot let any individual block their efforts in coming closer to the Creator. If a person turns them off, then pick up a sefer, a good book on hashkafa and read; listen to a CD shiur on any topic, and they will connect with the spiritual jewels that belong to them, always.
Most of all, they need concerned, easy going people keeping a Jewish rapport with them and encouraging them.
Since Purim is coming up iyH, asking them to participate in all the activities would be a nice plan to begin the rebuilding process.
By letting them take from the “spiritual buffet” what they like, and have a positive experience, eventually they will want more and more, beH.
I totally believe the statement that those who grab onto a branch of the tree of Torah, will grow beyond what they ever expected. This process is happening everyday to more and more people.
Hatzlacha to them!!!