I think I’m mainly with Clive here.
Intelligent design is bad science. It attempts to show that evolution is incoherent and cannot explain the emergence of the eye or the brain or complex living organisms and that these must require an intelligent designer. Dawkins in The Blind Watchmaker and elsewhere does an excellent job of demolishing this case on scientific grounds. Evolution is a beautiful theory that explains the origin of complexity from simple forces. If there are arguments for the existence of God or gods the incoherence of evolution is not one of them.
The wellsprings of religion, however, are not purely intellectual- an attempt to understand origins and complexity- but emotional and social. In this sense, Dawkins’ The God Delusion is inadequate.
. Marxists should be sympathetic to why many people, probably still a large majority of humanity, subscribe to religious belief. Such sympathy should not be extended to those institutions that use religion to control and oppress.
Politically we should be for complete freedom of religious belief or unbelief and no discrimination or special treatment for particular beliefs. This means a complete separation of religion and state so for example young people are free to learn about evolution and other science without interference or censorship.
Religious belief should not be an impediment to being a member of a socialist organisation or taking common action against a common enemy. By giving people hope through struggle they will be less likely to look for vicarious reward through fantasy and concentrate on attaining reward and satisfaction in reality, using our conscious brains sculpted by evolution to master science and technology to create a world or worlds that previous generations would think of as heaven or God rather than the daily living hell of capitalist oppression and destruction.