Faith is ignorance. That's what we should call it. Christians who have faith in God are ignorant. They lack the education and the knowledge to realise that their religious beliefs, and indeed the very fact that they believe them at all, are simply not reasonable.

The Mormons took great pains to explain to me that they couldn't prove that God existed, and yet since I couldn't prove that he did not, both of our positions pointed to the existence of God. God, they said, wants us to believe in him, so we must have faith. We must believe in him without proof.

That is a simple argument and one in which, if it stood alone, there is very little you can find to argue. If the Bible said just three words, 'Believe in God', there would be absolutely no room for discussion. Believing in God would be a true position of faith.

And yet, the Bible does not just contain those three words. It contains many words, many books, and though we cannot disprove the existence of God, it is very easy to disprove the so-called 'truth' of many parts of the Bible. Disproving the Creation story and the Flood story is extremely easy. In fact there is so much scientific evidence that you might as well be trying to kill an ant with an atomic bomb. Knowledge of that evidence is what Christians lack. They are ignorant of it.

The Mormons have more problems than ordinary Christians because they have another book which is, quite frankly, a bit of a joke. Anyone who reads about magic golden plates, and mega-battles between two warring factions of Jewish settlers, over 2000 years ago, in what is now the USA, will quickly realise that this story has one or two hard-to-explain loopholes. When I put some difficult questions to the Mormons they not only refused to accept what I said, they even told me they did not want to listen to my points. They were ignorant of the problems of the text on which their faith is based, and they were happy to remain ignorant. Determined to remain so, in fact.

Most religious people do not question the foundations of their faith. Those foundations are their holy texts - the Bible, the Book of Mormon, the Qur'an, and so on. One of the two Mormons hadn't even read the whole of the Old Testament. I am sure he did not leave my house thinking that he would later look up the Bible passages which condone slavery, which I had pointed out to him. They asked to leave before I could ask them more, telling me they could better spend their time talking to someone else. Someone, no doubt, less well-informed about their religion than I was. Someone more ignorant than them.

Christians who criticise evolution generally show startling ignorance of how it works. If they took the time to find out even some of the basic principles of the science they ridicule, they would not be able to use 'the eye could not just have appeared' or 'you say we all descended from monkeys'. At least with an understanding of evolution they could make a fair assessment, to see if science and their faith were compatible.

But they don't (actually, the Pope has, but don't tell the fundies!). They remain ignorant, and from that point of ignorance they claim to know better, and extol the virtues of faith. They believe without proof. They believe despite evidence which strongly makes the case that their religion is wrong, because they don't even want to look at that evidence. Many are afraid to look, it seems. Certainly one of the two Mormons was deeply troubled by my attempts to find fault with certain areas of his faith. When I asked him where God came from he said that he had considered the question but didn't even want to know. Not only did he not know the answer, he didn't even want to know the answer. That doesn't sound reasonable to me. Enjoying ignorance, embracing it, thriving on it, is all wrong.

I am ignorant of many things. I don't know much about advanced-level physics. I can't point out which tree is which in a forest. I don't know why women find it unreasonable for men to leave the toilet seat up (it's just as unreasonable and inconvenient for them to leave it down). But given the opportunity I would love to learn more about these things. Presented with knowledge, I would not turn my back and pretend it didn't exist. I certainly wouldn't tell other people that important information said one thing when it actually said something completely different.

Now I've started to touch on another aspect of faith. Faith is not just ignorance. Faith is deception. The ordinary believers are less guilty of this than are the ones preaching to them in their churches. The people on the pews believe what they are told because they are told with authority, by a preacher they have no reason to doubt. The preacher will be highly selective in the information given to his audience, keeping them in ignorance. But he will often mislead them, by telling them half-truths, or even downright lies, about views which are contrary to those of his religion.

Do you think, for example, that the people who run the Creation Museum in Kentucky really do not know that evolution does not suggest that animals evolved purely by random chance? We all know that they realise what the real science tells us, and yet they deceive the people who look to them for knowledge, by giving them lies. This is deception, through and through.

Another example. Everyone knows that the prison population in the US is predominantly Christian. Yet many Christians say that these are not 'true' Christians. The evidence is there, and yet it is ignored or, worse, used to 'prove' that the only 'true' Christians are the ones who don't break the law. Again, deception.

One of the greatest lies of all is that the US has such a high crime rate because of a decline in religion, when in fact of all the nations of the 'western world', the US is the most religious by far. This is more evidence that Christianity isn't the great cure-all it proposes to be, and yet every preacher in the land will blame the lack of morality of non-Christians for the ills of the world. More deception - lying about evidence which clearly shows the opposite.

When you hear someone tell you that he wants to share his faith with you, replace the word 'faith' with 'ignorance' or 'deception'. Then try to imagine what could possibly motivate someone to share with you his igorance, or spread the lies and deception which are necessary to continue believing in his Bible or other holy book.

Faith, ignorance and deception. In religion they are all interchangeable, and they are certainly the worst possible reasons for believing in anything, least of all the existence of God.