Religion provides hope
One common apologetic is the argument that religion provides hope, or meaning, or the assurance of the love of God, and that taking away a person's religion would be cruel. Hope is only of several psychological benefits that are claimed to be associated with religious belief.
Whether or not religion provides hope or meaning has nothing to do with whether it is true.
While previous small studies have had mixed findings, a large cross-cultural study of 8000 people in seven countries found a statistically significant connection between religious belief and major depression. 
Is this desirable?
This argument is comparable to the statement, "It would be cruel to take away a coke addict's supply, since that person would succumb to withdrawal pains". While this action would likely cause temporary pain to the addict, in the long run, the former addict would benefit greatly from eliminating his dependence. Similarly, it is better to be able to find hope and meaning without having to resort to religion.
Religion also provides fear
This argument also ignores the fact that for many people, religion brings unhappiness, guilt is one example. In many forms of religion, people are told that having sexual thoughts is a sin and for younger people with average sex drives avoiding sexual thoughts is likely to be difficult or impossible. A wide range of sexual actions, even feelings outside marriage or even within marriage are considered sinful, further homosexuals are told that they are vile and wicked. Some denominations preach that all humans, no matter how much good they do, are miserable sinners who deserve to be tortured for all eternity.
The hope that such religions provide is not the uplifting hope of improving one's future, but rather the hope of evading just punishment.
Many forms of Christianity teach that the majority of mankind will go to Hell. The fear of this may cause great distress. If you are on death's door and were raised to believe that you may be going to hell, it can create great stress. It can also use up energy that could have been spent better possibly saying goodbye to loved ones or even fighting whatever life-threatening condition is affecting you. It causes friends and relatives stress to think that perhaps a loved one that died could be in hell. It is difficult to estimate how much stress and unhappiness is caused by the fear of hell and the suffering that one is supposed to endure while in hell. Many people may be reluctant to admit how much they fear that they are sinners and could be destined to go to hell as well as the fear they hold that loved ones were sinners and are in hell. The fact that hell is forever, its hard to even imagine. Many may be uncomfortable outside on a hot day or sitting in a boring meeting, yet hell is portrayed far, far worse than these daily annoyances that many may try to avoid.
Religion also causes fear of supernatural horrors in this life, many people believe that witches, demons, or evil spirits are sabotaging their efforts or plotting to attack them. Normally, one would try to get a person to disbelieve in, or at least forget about, these sorts of paranoid delusions, however, if they are a member of a religion that accepts or even encourages these sorts of beliefs, it may be very difficult to convince someone to let go of them.
Religion can also cause fear of non-believers or believers in different religions, because it demands loyalty to a particular ideology, and that that ideology be defended against all conceivable threats. This fear leads to needless prejudice and sometimes even violence. Even "moderate" religionists are often afraid of the decline of their own faith, even they can't relate this decline to any definite tangible harm to themselves or others.