What then do you constitute as a human person? Immediately after birth? 7 weeks? 3 months? 6 months?

I think you should be aware that it is not only Catholics who are against abortion. Of course it is a shame to say also, that there are many so-called Catholic politicians who supports abortion. This is the mystery of iniquity and salvation, where even among the 12 apostles, there was one who betrayed Jesus. Even non-Christian religions consider abortion a very grave crime.