Good point. I'm not an expert on racism, but it would seem that racism does have positive attributes, especially for the "in" group - social cohesion first among them. I'd argue that the racist hole left in Americans, anyway, was filled with it's opposite: tolerance. The only thing we don't tolerate anymore is intolerance (which, BTW, is a very good change).
The "shape" of the hole left by religion is more complex. I suppose the best way to describe it would be to compare all extant religions and see what they have in common. My lay-opinion is that they almost all give the adherent two things: a) an almost Newtonian, absolutist world-view, in which b) some sort of father or mother figure that will make everything all right (in the long run). So, it's a kind of certainty about one's own personal insignificance. It's an excuse to "let go".
From this perspective, ignoring differences in specific dogma, religion is actually far more realistic than humanism, which usually tends to stress individual importance. But most people (and I include myself in this) are not important. Heck, think of any of the most important people in history - will they be remembered in 1000 years? 10,000? On an even somewhat long (human) time scale, almost none of us matter.