Many, if not most parishes will have some sort of gathering place and that would be the appropriate place to have such a meeting.
A lot of the issue is dependent on who is the moderator of any discussion. There are a multitude of possibilities for such a discussion; and they do not have to revolve around a large part of the doctrine of the Church to be fruitful. For example, discussion of various programs for the poor; programs for work retraining; programs for addiction are just a couple of topics which are easily broached between different religions. Concepts such as marriage and what that religion views as to what constitutes a good solid marriage does not have to devolve into a debate over the sacramental aspects of it, and all can learn.
And if one wants to get into some of the basics of each religious belief, it would be helpful if a minister or their equivalent could be the presenter. Obviously, the pastor should follow up, not in a belittling way or negative way, but to show how, in following Christ, we have something they do not have.
Again, a lot depends on who the moderator is (should be the pastor) and who the pastor is. Someone on the outer fringes of the Church (and their are a few of them around) might not be the person I would want to listen to.