Answer:
Robert Lewis Dear's holds and ideology that abortion is wrong, and that abortion needs to stop immediately.
Explanation:
Because of Robert Lewis Dear's choice of where he committed this act, we can understand that this was not a case in which someone wanted to harm as many people as possible in a seemingly random place, but rather he committed these murders because of his stance on abortion. Abortion has been politically debated for years, and many radical Christians have been known to go to great and drastic lengths to stop what they believe is wrong. He picked the abortion clinic because he was hoping to stop abortions from happening and fight for what he believed in.
Hope this helps! :)
(This is a vague outline, you might want to add other reasons or examples, I hope this helps!)