I have to plead guilty to having used the phrase that Rebecca deplores. She is absolutely right, though. Her final paragraphs contain a challenge for all of us:
Every one of us is a continuous organism from the moment we are conceived to the day that we die. It is illogical that we be valued and protected under the law only for a part of that continuous process.
So the next time someone says to you, "Human life does not begin at conception," correct them and tell them that life indeed does begin at conception and what they really mean to say is "I don't believe the life that begins at conception has value." (And then explain to them why that stance is totally illogical.)
And if you must use the word "believe" when discussing the beginnings of life, please do not say, "I believe life begins at conception." Say instead, "I believe the life that begins at conception has moral worth simply because it is human."