A frequent false charge made against atheists is that we are simply in rebellion against our fathers. This is yet another canard and, like most such, is simply an ad hominem attack rather than an actual argument. Thus, a good first response can be:
"Plenty of believers have bad relationships with their fathers, yet still believe."
"Instead of engaging in personal attacks, why don't you just make your case? If you can."
"Usually, when someone gets personal, it's a sign that he knows he can't win the argument."
As with other ad hominem arguments, this one can cut both ways: It is arguable that believers believe in order to replace their inadequate real world father with a new, more perfect, imaginary father.
Like so many other "arguments" made by believers, it is circular because it assumes the believer's point (god exists) is true.
Therefore, one reply to this nonsense can be:
"In order for a person to reject god because he is a father figure, the person must first actually think he is a father figure. You actually have to think he created you, which means you have to think he exists."
"Atheists don't think he exists, therefore they are not simply rejecting him. One can't 'reject' something that doesn't exist."
If they accuse you of engaging in circular reasoning (by assuming god doesn't exist), you can say:
"No. You have made a false statement about how I think, and I am correcting you."
Atheists don't disbelieve because of emotion--that's the way believers think. (The fact that they make this "argument" is really just an admission of this.) We disbelieve because there's no reason to believe. Atheists take the reason and skepticism that believers focus on other people's gods and use them to judge all gods.