You don't think believing an act has divine sanction makes someone more likely to commit that act? Even if the desire predates the looking for justification, the fact that justification is so easily found helps pushes the person towards doing it, more than if there was no theological justification.
Kind of stretching the meaning of 'theology' to something so broad as to be almost meaningless (other than 'religion related') there. Its a bit like insisting that everything done by the weirder and more unpleasant Marxist groups in the 20th century was ultimately about philosophy.