Adam Hamilton does not call himself “pro-choice.” He prefers “pro-life with a heavy heart.” What that means, as he explains in his new book “Seeing Gray in a World of Black and White,” is that he believes abortion should be available and legal, that there are instances in which it might be necessary and that those instances should be very rare. Further, he says, the abortion debate has been too hot for too long, and that, as a Christian minister, his job is to try “to support people no matter what decision they make.” As an evangelical megachurch pastor in Kansas, a man educated at Oral Roberts University, Hamilton speaks carefully, aware that he’s staking out a controversial position.