You need to do waaay more reading on morality because it is so clear you are just shooting off the top of your cuff using common Christian apologist arguments against atheism that are super easily debunked.
Atheism isn't a belief in anything, it is a lack of belief in gods, specifically. A lack of belief is not the same thing as a belief.
"Morality", as you define it here, is always based on opinion, even in religious texts, that's why we have to interpret religious texts in order to figure out what is and isn't moral. You know, or when a priest says they're gonna go into deep prayer to figure something out, that is interpretation.
As well as, you will find atheists that believe in objective morality, the belief that we all are born with a certain set of morals, along with atheists that believe in moral relativity, which claims that morality is an evolutionary trait designed to enhance cooperation and survival. Personally, I think we do have a very, very, very small set of base morals, such as killing is wrong without a real, and then most of our morality is based on the specifics of each situation.
I don't think, like a good number of atheists, that religion is the bane of all evil, but I do think that religion is a tool that is utilized and abused by many who seek power and that our governments do nothing to curb that abuse of power. See televangelists, see Scientology, see the Mormon Church, see Jehovah's Witness, see gay conversion therapy camps. These are all modern problems caused by the way in which we allow modern religion institutions to exempt itself from the laws of the governing state.