You can never be absolutely certain that anything doesn't exist. But you can show that it's unlikely.

With respect to those meanings of 'human' that are relevant to the morality of abortion, any fetus is less human than an adult pig.

By all means let's be open-minded, but not so open-minded that our brains drop out. -this quote is actually found in Carl Sagan's book The Demon Haunted World: Science as a Candle in the Dark, where he attributes it to engineer James Oberg, who says he stole it from someone else.

Physicists have come up with other explanations. One is to say that these six constants are not free to vary. Some unified theory will eventually show that they are as locked in as the circumference and the diameter of a circle. That reduces the odds of them all independently just happening to fit the bill.

A delusion that encourages belief where there is no evidence is asking for trouble. Disagreements between incompatible beliefs cannot be settled by reasoned argument because reasoned argument is drummed out of those trained in religion from the cradle. Instead, disagreements are settled by other means which, in extreme cases, inevitably become violent. Scientists disagree among themselves but they never fight over their disagreements. They argue about evidence or go out and seek new evidence. Much the same is true of philosophers, historians and literary critics.

It could be that at some earlier time, somewhere in the universe, a civilization evolved by probably some kind of Darwinian means to a very, very high level of technology- and designed a form of life that they seeded onto perhaps this planet. And I suppose it's possible that you might find evidence for that if you look at the details of biochemistry, molecular biology, you might find a signature of some sort of designer.

I hope nobody is seriously suggesting that we get our morals from scripture because if we did we'd be stoning people for working on the Sabbath or switching on a light on the Sabbath. So the point is that you can find good bits of the Bible but you have to cherry-pick, you have reject the nasty bits and pick the nice bits.