While these groups have some common aspects, there is in fact a rather fundamental difference. Many people say that they hate religion, when more likely by “religion” they mean Christianity, Islam and Judaism (Abrahamic religions). Besides that especially “theist” is often a misunderstood word and misused in the context to describe religionists (people who practice religion). It is true that all religionists are theists, but not all theists are religionists. Religionists are often bound by rules set by their religion, while theists are bound only by a philosophical idea that there is some sort of deity that can be referred as “god”.

A theist can, for example, be a pantheist: a person who doesn’t necessarily believe in a conscious god, but does accept universe (all universes in the multiverse) as god. Surely a pantheistic logic is quite rational as all life is indeed created by universe’s laws of nature and ‘everything together’ is the only thing that can qualify as perfect as there is nothing to compare ‘everything’ to.

A theist can also be a deist and consider ‘God’ as some sort of a cosmic alien that engineered life and perhaps the universe itself. At first glance this logic might appear ridiculous, but scientifically considering the structure of first living organism and assuming it had 68 genes, the probability of these genes coming together into a functional ‘program’ is roughly one out of 10²²⁹ and this doesn’t include the probability of these nucleic acids forming all in one place and probability of this cell surviving in the environment it was born in. From mathematical point of view the existence of life, at least as we see it now, by an accident is close to impossible even considering all the planets in our universe. In this respect, claiming that deists are completely illogical is rather ignorant.