The Argument of Conscience
Since moral subjectivism is very popular today, the following version of, or twist to, the moral argument should be effective, since it does not presuppose moral objectivism. Modern people often say they believe that there are no universally binding moral obligations, that we must all follow our own private conscience. But that very admission is enough of a premise to prove the existence of God.
Not only is a premise for God but it allows for the backing of the moral argument itself to say that if we can act lawlessly in a fallen world, it must be morally permissible because morals are subjective but rather the logical rationale is that we are to abide by a LAWGIVER.
Now where did conscience get such an absolute authority—an authority admitted even by the moral subjectivist and relativist? There are only four possibilities.
From something less than me (nature)
From me (individual)
From others equal to me (society)
From something above me (God)
God is the only adequate source and ground for the absolute moral obligation we all feel to obey our conscience. Conscience is thus explainable only as the voice of God in the soul. The Ten Commandments are ten divine footprints in our psychic sand.
The most common basis for this argument is premise (2) that we are bound to what our conscience tells us to do. The second premise is that the only possible source of absolute authority is an absolutely perfect will, a divine being. The conclusion follows that such a being exists.
How would someone disagree with the second premise? By finding an alternative basis for conscience besides God. There are four such possibilities:
something abstract and impersonal, like an idea;
something concrete but less than human, something on the level of animal instinct;
something on the human level but not divine; and
something higher than the human level but not yet divine. In other words, we cover all the possibilities by looking at the abstract, the concrete-less-than-human, the concrete-human, and the concrete-more-than-human.
All of these fail to adequately provide an ultimate source and authority for moral conscience. None of these objections can actually account for the authority.