The very nature of government is to pass laws. When a law is passed it inevitably limits the rights of someone in order to protect other people's rights. Every law limits the rights of someone. For instance, there are traffic laws that make it so that I cannot go whatever speed I want nor can I run through red lights. Those laws limit my rights for the better good of society. Making abortion illegal would limit the rights of those women who want to have abortions, but it would protect the rights of the baby in their womb. Rights are limited but it is to protect others and create a better society. There might be a better parallel to abortion than traffic laws but the purpose of that illustration was just to show that every law limits freedom, hopefully for the better good of society. A bad law is one that limits freedom and does not provide for the better good of society.
It really comes down to one's belief on when life begins. It would be horrible for someone who thinks that life begins at conception to not stand up against abortion. Would you respect someone who justifies away murder for an individual's liberty? Pro-lifers are just doing what we would expect any upstanding person to do if they held the same beliefs.
Obviously, if one does not believe that life begins at conception, they do not believe they are murdering the baby. Both sides need to see things from the other side. A pro-lifer needs to understand that the other side believes that life begins at another point. A pro-choicer needs to understand that pro-lifers are just standing up against what they believe is murder. Both are standing up for what is right based upon their belief of when life begins. The only evil individuals would be those who believe that life begins at conception and still wants to abort a baby or those who believe that life begins at birth but wants to ban abortion.
I believe that anti-abortion activists should be more willing to pay the bill for those who they demand should not have abortions. It is the responsibility of Christians to sacrifice themselves, even for those who make irresponsible decisions. That is the example Christ showed on the cross. Christians should be willing to put their money up for the women who would not be allowed to have abortions. A pro-adoption campaign would probably benefit society more in the current environment than an anti-abortion campaign.
Also, the representatives and senators have passed anti-abortion laws that the Supreme Court has overturned. The only way to have those laws enforced would be to have a President who would nominate a Supreme Court that would allow the laws to stand in the books. Our nation is about only one justice away from that happening.
In the end, I do not know how science can answer the question of when life begins. It is strictly an ethical question that stems from one's religious beliefs, whether completely secular or based on some religious tome.