Buddha is NOT a God. The "Buddha" that you are referring to might be "Śākyamuni"? He's the founder of Buddhism but he is NOT God. He's like a teacher of Buddhism, sorta similar to the prophets in many of the religion but he is NOT Buddha even though he's being regarded as one by many but that is NOT correct. And all those multiple deities in the so called metaphysical form with all those statues that you see people pray to in those temples only exist in folklore legends but in true Buddhism, they all represent an ideal. Buddhism is a bit complicated in that it exists in two different forms, the traditional "folklore" form and the spiritual or the true form.
Any system of beliefs that encompasses for example reincarnation and progression to an immortal non-corporeal form must be a religion. What else could this beliefs be?
A natural progression of biological beings after death that we just have not been able to prove with our scientific technology? Regardless, still MILLIONS of MILES of difference from Islam. LOL
Until an after-life can be proven scientifically, it is taken as a matter of faith. And that's a religion. A person may follow Buddhist principles with regards behaviour. Another might follow principles of behaviour set down by the Jewish faith. But that does not make the one a Buddhist nor the other Jewish.
So if a doctor tells you your illness is due to a nano-virus that cannot be seen by any existing microscope and you can't see it, does that mean that doctor is practicing a religion when giving you the diagnosis? LOL
I am sure the doctor would be able to call on the latest scientific research to justify his conclusions that the nano-virus existed and caused the illness in question. But this is just a dry debate over conclusive or circumstantial evidence in the scientific or legal context. Religion is concerned with matters of faith for which evidence is irrelevant, and for which the deliberate seeking of evidence wold in any case be a matter of apostasy, and specifically with the existence and actions of immortal beings on a "higher" plane of existence than our own, i.e. gods. Also with the question of what happens to human consciousness or the human soul after physical death of the body. So not all matters taken on a degree of faith due to lack of conclusive evidence can be called a religion. But all systems of belief that form a framework or context for issues of world creation, deities, immortal beings, afterlife and reincarnation or progression of the soul after physical death to a "higher sphere" are religions. Anyway, I am confused as to why anyone would think buddhism is not a religion. What separates it from other major religious belief systems?