Professor Michael Reiss, who is also an ordained minister, said creationism should be discussed in science lessons "if pupils raised the issue", according to the BBC.
He didn't actually say creationism should be taught in science lessons, but his belief that it should be discussed got scientists twitching.
The Royal Society says in a statement:
As a result, Professor Reiss and the Royal Society have agreed that, in the best interests of the society, he will step down immediately as director of education – a part-time post he held on secondment. He is to return, full time, to his position as professor of science education at the Institute of Education.
The BBC says the Royal Society "reiterated that its position was that creationism had no scientific basis and should not be part of the science curriculum".
But the society says, "However, if a young person raises creationism in a science class, teachers should be in a position to explain why evolution is a sound scientific theory and why creationism is not, in any way, scientific."
See also this from The Times.