Absolute Truth <-> God
It’s an untrue assumption that “absolute truth” is equivalent to a religious person’s God. This is self-evident by virtue of their being so many religious sects within denominations and religious groups. The question assumes that the atheist does not believe in objective moral standards or absolutes which can be true, false, or uncertain. You can be an atheist and believe in absolutes: Atheism is the rejection and-or lack of a belief in a deity or deities. This is why atheists can be accused of having dogmatic beliefs. Further, it is wrong to assume that belief in a deity is a necessary requirement to have moral views and that the deity itself is in fact the substratum for morality. This is obvious by virtue of the epistemological dilemma of knowing the deity’s true nature. You can only assume the deity is moral in the way that you are moral or that religious groups are moral. Simply because a book says the deity is moral, it doesn’t follow that the deity must be moral.
When atheists say “whatever makes me feel good,” this is the same argument that the religious makes. It’s a common sense one—it is such because all atheists and theists are agnostics. Indeed, it is necessary for a theist to be an agnostic for them to have religious belief. Belief and Knowledge are disparate domains. When we call a religious person a dogmatist, we do not mean: You have dogmatic and absolute views on what you Know. We mean: You have dogmatic and absolute views on what you Believe.
Religious people believe they know their deity’s nature, but they do not know it. That being the case, they only believe their moral views are true, and this can be contested. Therefore, there is no reason to use the religious worldview as the default by which all questions of morality should be asked. There is no reason to assume their worldview true. Most people do this anyway, in their inquiries, because the popularity of religion and social coercion inclines them to do this.