Myth:
You think that the church is evil, and just want to knock it, and God.
Response:
It is true that there are people who have become atheists due to anger at their church and/or religious institutions generally. It is also true that some of these same atheists have not let go of their anger even today, allowing it to influence their critiques of religion and theism. It's wrong, however, to conclude that therefore atheism is necessarily or inherently an act of rebellion against church and religion. Many, if not most, atheists come to atheism via means other than rebellion.
The simple principle here is that no one should assume that what's true of some atheists, or even all the atheists one encounters, must necessarily be true of all atheists. Atheists are a very diverse group and they do not hold a large number of opinions in common. Some atheists, in fact, even regard religion as a good thing. On an institutional level it often causes problems, but on a personal level some believe that it gives great support and succor to its members.
It's common for atheists to argue that religion is bad and that Christianity is wrong, but that's more a product of Western cultural trends than a product of something inherent in atheism itself. Christian theism so has dominated Western culture, politics, and society that there have been few sources of religious or theistic resistance to this domination. Because of this, atheism and atheistic groups have been a primary locus for freethought and dissent from Christian authority and Christian institutions.
This has meant that most people engaging in such resistance have ended up being pulled into the sphere of irreligious atheism rather than into an alternative religious system. Atheism doesn't have to be irreligious nor does it have to be anti-religious, but cultural trends in the West have caused atheism, irreligion, and opposition to religion to be drawn together in such a way that there is now a high correlation among them.
More importantly, however, it should be remembered that theism and religion are simply not the same thing. Some religions are atheistic, and it certainly cannot be assumed that members of those traditions are only atheists in order to knock religion and churches. Critiques of religious beliefs and critiques of theism itself may often be related, but they are nevertheless separate issues.
Atheists simply don't believe in any gods. They may regard theism as nonsense, or they may simply not care. They may regard religion as harmful and religious institutions as dangerous, or they may not care. Atheists are all different, and simply knowing that someone is an atheist does not entitle one to make assumptions about their opinions regarding religion, politics or anything else for that matter.
Myths like this are often used by religious theists in order to dismiss atheistic critiques of religion as well as atheists themselves. It seems to be assumed that if a person's atheism is just a form of rebellion and based on a desire to attack religion or church, then their critiques must not be reasonable and don't have to be taken very seriously.
The truth, though, is that a person's motivations are irrelevant. When a theist relies upon this as a means for criticizing atheism or as a means for dismissing atheistic critiques of religion, they are committing the Genetic Fallacy — a form of ad hominem logical fallacy. The origins of a belief or idea have no bearing on the truth, reasonableness, or justification of that belief or idea now. Bad ideas can have good and reasonable origins while good ideas can have bad an unreasonable origins.
If atheism is unreasonable, it's not because of anyone becoming an atheist out of rebellion against their church; if atheism is reasonable, that's not negatively affected by anyone becoming an atheist out of rebellion against their church. Thus this question is ultimately irrelevant to the most important issues and is only brought up as a means of distracting our attention from those issue — and perhaps because of a person's inability to address them in a more substantive manner.
