
When it comes to opposing same-sex marriage and abortion -- staples of the political Right -- conservatives report their religious backgrounds as important influencers of their decision making, which makes sense. The Bible has spatterings of passages condemning homosexuality -- Leviticus 11:22-23 perhaps being the most commonly cited -- and the New Testament in particular speaks to the sanctity and importance of human life.
Those same passages that support the preservation of life likely lead conservatives to shy away from religion as an influence on beliefs surrounding the death penalty. Consequently, liberals find their religion on this issue because there is greater support for the political Left's view, namely the condemnation of the death penalty.
I don't have a problem with either side cherry picking from religious doctrine in this manner. Anyone who believes wholeheartedly in any philosophy either founded it or is too damn foolish to question it meaningfully.
I do think, however, that it is important to admit that religion is referenced only when it is personally, socially or politically expedient. This selective use means that religion -- at best -- informs our decisions, it doesn't dictate them.
If we can look past belief to justify our positions when necessary, then belief is not enough to codify our positions into law. In other words, a secular society should and does depend on reason to establish law. Religion alone is not enough.