Morality arguments make the case that morality cannot exist without a divine author.
This usually follows the lines of:
1. Absolute morality exists
2. This must morality must come from somewhere.
3. Therefore, the maker of this absolute morality must be God.
There are several problems with this argument. Firstly, is the assumption that absolute morality exists. There is no one principal that 'ought never be violated'. Most people agree that murder is wrong, but we can come up with many hypothetical situations where murder might be justified, legal and even good. Most rational thinkers agree that it is not the action, but the justification behind the action that matters.
Secondly, this explaination is not sufficent to explain the apparant lack of morality in say, a sociopath, or the fact that atheists and others amongst the godless congregation do have morality despite not being theistic.
Point two is absolutely correct. This morality must come from somewhere, and there are hundreds of explainations for this, see secular morality for some examples. We can see in nature how morality evolves naturaly, so there is no need for a divine intervention.