In answer to the letter, "Bible is mute on abortion," I'll agree with him that the word abortion is not in the Bible. But the Old Testament is not silent on life in the womb.
In Psalms 139:13, "You created every part of me; you put me together in my mother's womb." Verse 15, 16a: "When my bones were being formed carefully put together in my mother's womb, when I was growing there in secret, you knew that I was there – you saw me before I was born."
This is not a bunch of cells but "I" - a person.
The New Testament has the example of the Virgin Mary, going to visit her cousin Elizabeth who was pregnant with John the Baptist. In Luke1:44, Elizabeth says to Mary, "For as soon as I heard your greeting, the baby within me jumped with gladness." Here you have an unborn baby leaping with joy when he recognizes Mary's voice.
This is an unborn baby that some believe they have a "right" to destroy.