I am the furthest thing from any kind of religious zealot and I believe that life begins at conception. I base my belief purely on scientific fact that an egg and sperm combine and immediately begin to define the process of what will eventually replicate and combine new cells into a mini human. It's a natural,natural biological process that can be seen in the majority of species of life on our planet. Its Life no matter who looks as it and being a process of nature is where we get our bill of rights. Those rights listed are natural and not given to us by a government. The very fist right is "life". These are not things that only religious zealots believe or force upon others. Do not forget that founding fathers of the USA were all "religious". Many of them were in fact atheist and that was a driving factor as to why they left the English homeland. To get away from state sponsored religion. To practice or not practice what they personally chose.
Throwing out a generalization of it being a religion exclusive item is 100% false. I know many atheists in real life who would debate you till you drop on this.
All life on this planet is special and should be cherished, loved and cultivated. Whether its a tiny mushroom, African Elephant or a Homo Sapiens. It should not be thrown away for a little regret of sexual satisfaction last night.