I was wrong about homophobia being a purely religious thing. Mr E's example isn't really good enough, but there are ones, like in mainly secular Asian countries which place enormous emphasis on family.

But abortion, not so much. You may be killing a living human, but without an idea of the "soul" and without the black-and-white commandment from on high not to murder, what's happening is akin to the killing of an animal. A foetus may be a human, but it is no more sapient than a crab (and probably less). It is certainly not a human person. I'm not saying nobody would argue against abortion, but I'm saying that without the religious arguments against it, it's really a fairly simple discussion.