This is a very philosophically deep question...
I think this depends on what the term "wrong" really means, that can be rather vague. It seems like a rather basic label...
I don't personally see anything wrong with it. There is nothing wrong with a parent trying to force an opinion on to their children because it is their children and it is their right to try and shape their children the way that they want them to be. Every parent does it in some form and every parent will do it, that is human nature. Just like when people try to sway another's point of view in every day life.
There is something wrong with saying to another person's child that there is no God because you don't really have the right to do that, but to say it to your own child, I see nothing wrong with that.
Besides I don't think it would really matter in the end, the child will be raised by the parent whether they like it or not. A parent does not have to verbally voice their opinion to a child to make them believe it and influence them.
A psychopath is not raised because their father said that it is ok to beat women, it is because they witness the behaviour of violence. A child would be influenced the most by the way their parents act, not by what they say. If a parent is athiest, their way of life will pretty much influence the child no matter what they say.
I personally believe in no God at all and the way I raise any child of mine, whether I verbally state the existence of a God. I'm pretty sure the child is going to follow my opinion whatever I say anyway, its not like Im going to make the child go to church and the child will have no religious influence, so I fail to see how the child could have an opinion otherwise.
This is like saying that its wrong to tell a child your point of view on anything, which seems rather silly.
If however this is more a question of respect, it is wrong to say to a child that there is no God AND anybody who thinks otherwise is an idiot. That is wrong, because it going down the path of discrimination and no respect of the rights of others. But to simply say that there is no God, there is nothing wrong with that.
P.S. There is no God