Can somebody who doesn’t believe in God still do good things, that is, act morally? The answer to that question is “yes, of course.” But when the issue is the existence of God, asking if an atheist can be moral leads the discussion down a rabbit hole.
The question should be this: How can there be objectively true and universally applicable moral laws if there is no God? If there are such objective moral laws, then there must be a God. We know there are such laws the instant we realize it is always and everywhere wrong to, for example, torture children.
Why is this important, especially if you work on Capitol Hill and are thus part of the process by which America debates and establishes its laws? The answer to that question is in the following video from philosopher William Lane Craig’s Reasonable Faith: