This is something I have been wondering about for a while now. The reason is that I find myself pulled in both directions on this question. On the one hand, it does seem to me that religion and superstition are very closely aligned and have many of the very same psychological and social well-springs. On the other hand, I happen to know a fair number of devoutly religious people who are also among the least superstitious people I know. They are, for the most part, academics at a Catholic university and are far less superstitious than the human average. Of course, the Christianity they espouse is of a particularly refined variety.
It seems to me that, compared to superstition, religion is a far more complex social phenomenon. This means that whereas superstition might have at heart the satisfaction of a narrow range of human needs, religion satisfies a much greater range of needs (both social and individual), depending upon the particular believer or society and the particular variety of religiosity. Certainly, there does seem to be overlap. When someone crosses themselves to protect them from evil spirits they are both being religious and superstitious. The idea behind christening seems to have much the same sort of warding off role, even if ‘the evil spirits’ have been abstracted away to the level of ‘original sin’.
I guess that to a significant degree, the answer is going to depend upon what ‘religious feeling’ is supposed to be, as this often seems to be the basis that relatively enlightened religious people seem to build their religiosity upon. Of course, in a sense, I do not know what that feeling is like, not having every felt anything that I have identified that way. Still, from the descriptions given, it does seem to be a feeling of wonder. As such, it does seem to be a long way away from superstition, which seems to mainly arise out of fear and the desire to feel in control. Not that, of course, those feelings do not motivate religious beliefs in some cases, such as the desire for eternal life caused by a fear of death.
Also, superstition does not seem to have much of a social role whereas religion, through its institutions, is one of the most significant social forces. So, I guess, the answer seems to be that religion and superstition do have to be treated and understood separately. And the claim that religion is just superstition is too hard and fast. This does not mean, of course, that it is rational to believe in God. That question I haven’t considered here at all.