Every doctor knows that life begins.... at conception. Here is an intellectual challenge to your "brilliant" brother.
Draw a line across a piece of paper, all the way. A vertical line at the left end is labeled "conception."
The vertical line at the far-right end is labeled "Live, healthy birth."
Give him the pencil and ask him to draw a line splitting the precise second when LIFE BEGINS and you can no longer kill this unique human being, produced by a man and a woman. He must provide his "intellectual logic" for his location.
Tell him "Before you were conceived in the womb, I knew you." - The Lord God
P.S. The Unabomber was a genius. What did that profit him? Murdering people with bombs, living in a filthy rathole cabin, alone and bitter. He had a well-worn copy of Earth in the Balance by Al Gore and a copy of Two Volume Guide to the Bible by atheist Isaac Asimov, another bitter atheist like Unabomber.
Incidentally, Asimov's son, in Northern California, was convicted of child pornography on his computer drive, a highly illegal and morally offensive act. Would Asimov be proud?