Atheists proselytize and preach too
This argument is generally made to act as an example of hypocrisy. Some atheists may proselytize like believers, but they are by no means indicative of all atheists; indeed, many major atheists (such as Dawkins) refuse to debate theists. Often atheists are simply responding to challenges or insults made, but those that do seem to preach are not teaching what to think, but more how to think: not inherently arguing for atheism, but rather arguing for essential facts such as the correct age of the Earth and evolution, as well as the scientific method over blind faith. Those who follow the scientific method generally win arguments against those who follow blind faith which makes religious people very vulnerable to freethinkers. Believers try desperately to get atheists to stop arguing and complain that we are strident atheists.