Actually what the Constitution says (that's relevant here) is:  "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; "  The question as to whether abortion is murder or not hinges on whether the mother's life or the child's life takes precedence.  Some credible religions, notably large segments of the Jewish faith (but not all segments), give precedence to the mother because she gives life to the child.  Under the constitution as explicitly written you are free to hold an opposing position (as you and I do) but we are not allowed to prohibit others from freely exercising their beliefs.  Rather than promote my belief by law (i.e., mixing church and state) I prefer to challenge moral beliefs of those who do not share my positions and convince them of the soundness of my beliefs.  It promotes truth and preserves free will, something that laws can't accomplish.