Necesito - even if you believe an embryo is a person and that therefore (all other things being equal) killing it or allowing it to die is as serious a matter as killing or allowing to die a human being who already exists, it still doesn't follow that abortion is murder, for the reasons Saskia points out
If we have a person attacking us in such a way that we genuinely fear for our lives and self defence reasonably involves lethal force, then we are not guilty of murder. The same argument applies, even if you believe an embryo is a person, to a pregnancy that kills the mother.
I might be the only tissue match for a bone marrow transplant to save my brother's life, and the bone marrow transplant might well be non lethal (though invasive and painful). The fact that he would die otherwise doesn't mean I should be compelled to undergo extraction of some of my bone marrow. Nor does it mean that I would be guilty of murder if I refused. Likewise the fact that the embryo would die if removed from my body does not make abortion murder even if one accepts that an embryo is a person, and no-one should have the legal power to compel me to undergo the risks of physical harm, hardship and possible death involved in pregnancy.
Even for a Christian, given that theologians have spilled gallons of ink defending the concept of the just war (in which innocent civilians, children and pregnant women among them, die as a "foreseen but unintended consequence" of the choice to go to war) you can't just assert "abortion is murder."
Not without an argument as to why it's different from self defence, why we don't compel kidney or liver or bone marrow transplants, not without an argument as to why it's morally different from a just war in which innocent people die.
For the record I don't think embryos are "persons" in the sense normally used in moral philosophy.
But even if they were, it's commonly accepted that not all killing is murder, so you have to do the work in demonstrating why you think it is in this instance.