There is nothing religious about a law against abortion. The law prohibits abortion after a specified period of time--15 weeks in the Dobbs case. That makes the action illegal just like theft, rape, sex with a minor, or child pornography is illegal. Whether religion is a factor in wanting those things to be illegal is irrelevant from a constitutional perspective.
11% of atheists oppose abortion. Is that religious?
I did not say abortion is murder. I used murder as an example of a criminal law that most religions also oppose (use theft, instead).
But murder is what the criminal law says it is. A murder statute could be written to include abortion if a state chose to do so.
Again, it doesn't matter if my political beliefs are based on my religion. The establishment clause is based on the law itself, not my beliefs. But not all anti-abortion people say life begins at conception. Some state laws against abortion make it illegal after 6 up until 15 weeks. Atheists who oppose abortion don't base it on religion.