I wouldn't say "evil", as that involves a certain element of intention, but I would say that inherently it causes harm even just by introducing bogus premises. Garbage in, garbage out, really. The most valid logical inference will still produce an unreliable result if based on false premises.
Note that by "harm" I'm not even talking about the crusades, or the exorcisms in Africa, or the witch camps in Ghana, etc. Those are easy targets. But even if we don't get bogged into those again, there is actual harm even beyond that.
Giving people hope sounds good and fine, but what about detrimental actions that such false hope influences? E.g., hope that their rabbit foot works is what makes people bet their lifetime savings in Vegas.
The fact is that at every moment in life you take choices like "do I do X, or do I do Y?" and then look at the pros and cons for X and the pros and cons for Y, when actually deciding that. Adding some false hope or an illusionary safety net to one column just makes that choice artificially better or safer, and may cause a decision which is not actually the best course of action.
It would be harmless if people actually took their decisions based only on the real stuff, and then only used religion as a comfort afterwards. But it's not that decoupled. Those false promises are factored in even in taking the decisions, and can skew the results. Badly.
E.g., think of all the battered wives who find the comfort and strength in Jesus to... not just stay with some abusive drunk, but keep their kids with that abusive drunk too. They're not just finding some comfort in the idea that they'll get some rapture bonus points for it. They're finding a reason to continue that bad course of action, and ruin not only their own lives, but often their children's lives too. It's not just some comfort, it's actually distorting the actual facts used to take a decision, and allowing the bad decision to win.
Or on grander scale, religion is not just what made us herd some people in ghettos for half a millennium, but also what made them accept to be herded in ghettos if the alternative was to stop pleasing a non-existent God. It's actual "do I do X, or do I do Y?" choices where someone's imaginary friend was not just a comfort, but a reason to pick the most self-detrimental choice.