These ideas, which brook no dissent, give rise inescapably to intolerance and indeed to tyranny. Indeed, they are far more tyrannical in their effect than the God of the Hebrew Bible who gets such a bad press for being so authoritarian. In fact, he has a truly terrible time getting his way. His people are always complaining, refusing to do what he tells them, blaming him for everything and always, always arguing with him. But ideologies which represent the will of man bend everything to the governing idea, which cannot be gainsaid. There can be no argument with them.  

Rather than being rational, I suggest these are irrational; not tolerant at all, but deeply illiberal; not open to other ideas, but as dogmatic as any medieval pope. Indeed, these atheistic ideologies are reminiscent not just of religion but of medieval persecutions, witch-hunts and inquisitions.

Let me illustrate all this with an anecdote. After a debate in which he took part some time ago, I pressed Richard Dawkins on his belief that the origin of all matter was most likely to have been an entirely spontaneous event — which meant he therefore surely believed that something could be created out of nothing. Since this ran counter to the scientific principle of verifiable evidence which he tells us should govern all our thinking, this itself seemed to be precisely the kind of irrationality which he scorns. 

In reply, he acknowledged that I had a point but said that the alternative explanation — God — was more incredible. But then he remarked that he was not necessarily averse to the idea that life on Earth had been created by a governing intelligence — provided, however, that such an intelligence had arrived on Earth from another planet. Leaving aside the question of how that extra-terrestrial intelligence had itself been created in the first place, I put it to him that he appeared to be saying that "little green men" provided a more plausible explanation for origin of life on Earth than God. Strangely, he didn't react to this well at all.

However, Dawkins is not the first scientist to have suggested this. It is a theory which was put forward by no less than Professor Francis Crick, one of the discoverers of DNA.

A committed atheist, Francis Crick found it impossible to believe that DNA could have been the product of evolution. In 1973, Crick and the chemist Leslie Orgel published a paper in the journal Icarus suggesting that life may have arrived on Earth through "directed panspermia". According to this theory, micro-organisms were supposed to have travelled in the head of an unmanned spaceship sent to Earth by a higher civilisation which had developed elsewhere some billions of years ago. The spaceship was unmanned so that its range would be as great as possible. Life started here when these organisms were dropped into the primitive ocean and began to multiply. Subsequently, Crick abandoned this theory and returned to the idea of the spontaneous origin of life from purely natural mechanisms.

How can someone so committed to reason be so irrational as to entertain such a fantasy?