Disclaimer: I am not a Theologian, but I will try to make my case based on what I do know of religion
God's gift to mankind was the gift of free will. It is what separates us from the Angels; God's first creation. Unlike Angels, who are infallible servants of God, God favored man and gave us God's most precious endowment; independence. God makes this point clear in Genesis when Adam and Eve were allowed to choose temptation over the word of God. God provides all of us with a map to salvation; we can choose the road that leads there or take the one that leads to damnation. However, God has made it clear that it is our choice to manifest our own destiny. Whether any of us believe in organized religion, all of us agree in the free will of man. It is this freedom and personal independence that inspired the founding of our great country. This, above all, is how the bible influenced our founders, not the 10 commandments. It is what the Bill of Rights emphasizes; our rights to control our own destiny.
In fact, the Framers of our constitution expressed this freedom when they sanctioned the right of every American to choose who, what, and if they worship. They made it clear that it is every man's right to have a personal relationship with their deity. Our government is one of laws, based on community standards, not religious tenants. Laws, generally speaking, are enacted to protect people from the acts of others. These laws are to protect others from being victimized.
Judeo-Christian religions teach us that we are solely responsible for our own salvation/enlightenment. We are not to judge others based on their beliefs, nor are we bound to ensure the salvation of others. We were all born destined to flaw and have been granted the option to seek forgiveness and redemption, but, again, it is a personal choice.
Given this interpretation, I have a hard time understanding, if we were born to sin, why does organized religion insist on laws that will "protect" us from sin. In my view, in the view of our founders, and in the eyes of God, we can make a choice to sin, provided we do not hurt anyone else in the process. God's laws specifically detail reparations for crimes against another, but crimes against God are up to God to pass judgment. From this, we can see why Murder, while a sin, falls into the category of law.
Anti-choice advocates categorically denounce abortion as a mortal sin, granted there is a huge debate about when life begins, but it is a sin which primarily affects only the person who is receiving the abortion. If you believe that it is a sin, then you should believe that God will punish the sinner, but it is not your place to gaze back on Gomorrah, lest you be turned to salt as well. In other words, it is not your place to worry about another's relationship with God. In fact, by passing judgment, you have built a glass house from which to throw your stones. I respect the beliefs of all, whether you are pro-choice or anti-choice, so long as you are choosing for yourself. As a man, I have no place interfering in the free will of a woman in these matters. I can offer advice, if asked, but I will not force my beliefs on another.
The same can be said about drugs. I do not like drugs, illicit or prescribed, and I have witnessed, firsthand, the affects of substance abuse on the user and those around them. I am a pragmatist and I know that prohibition does not work. It has not stopped the free flow of drugs into our country. In fact, in protecting society from one sin, we invite many more that support the illegal drug trade. Religion is frequently used to vindicate the prohibition. People frequently claim that not outlawing its use constitutes a government endorsement of drugs. Instead, I say that legalizing drugs is not an endorsement of narcotics, but rather it is an endorsement of God's gift of free will.
Ask yourself the following questions
Has another person's abortion directly affected your life?
Are drug-related crimes and their fallout worth disallowing people the option to legally make a personal choice?
Is it the role of government to protect man from sin?
If you answered yes to any of these, please explain where my logic is flawed.