Religious ethical theories are no improvement on secular ones.
Followers of St. Thomas Aquinas argue, for instance, that human beings are essentially reproductive and that therefore homosexuality is wrong. But if human beings are essentially reproductive and homosexuals are not, what follows is that homosexuals are not human beings. Since homosexuals are human beings, human beings are not essentially reproductive. The fact is that you cannot use a property to categorize things and then criticize the excluded on the ground that they lack it. Catholics constantly equivocate.
Adherents of the divine command theory have no alternative but to maintain that revelation of some sort or other provides the only reliable guide to morality. If God is always truthful, then revelation is reliable. The trouble is that a necessary condition for establishing that something is in fact a revelation from God is establishing that it is entirely true. Consequently, either they end up effectively maintaining that we know that it is true because it is from God and that we know that it is from God because it is true, which is a case of circularity, or they commit petitio principii by dogmatically affirming a clutch of moral injunctions that suit their prejudices. Either way, revelationists beg the question.