While I regard all deities as mythological, I have no problem if other people believe in some divine being's literal or actual existence. "Whatever floats your boat and harms none" is my philosophy. However, there is a very real danger in literal belief if it is also accompanied by another belief, namely, spiritual or religious supremacy, which holds that Only One Truth exists and therefore every other belief is Wrong and Heretical.
From that supremacist belief flows all manner of evil. It becomes permissible (indeed, often a duty) to shun, condemn, exclude, punish, torture and/or kill non-believers. Proselytizing and conversion, even forced conversion, are seen as admirable. Wholesale destruction of non-believers' beliefs, culture and lives is encouraged. Anything goes if it elevates and strengthens the supremacist position.
All major religions are guilty of this. Historically, Christianity is a prime example. Around the world today, Islamic supremacists wreak havoc in various countries. Judaism still teaches that only they are the Chosen People. Buddhists are not immune from this evil either, as evidenced by the ongoing persecution and genocide of Rohingya Muslims in Myanmar. Hindus and Muslims have long been at each other's throats in India and Pakistan.
And it's not just persecution of non-believers. Supremacist doctrines, whether concerning religion, gender or race, usually bond together like cement for even more devastating effect. How often has religion been used to justify theft, subjugation and exploitation of other races? Virtually always. What religion has historically treated women equally, or even well, compared with men? None whatsoever. Supremacist thought of every variety is toxic to human welfare and freedom, plain and simple.
The opposite of supremacist thought in religion is known as Universalism (today often disparagingly referred to as "moral relativism"). Universalism holds that spiritual truth, healing and salvation (to use the standard religious terminology) are available to all, regardless of what religion (or none) is practised. The foundational principles of Universalism are tolerance and respect.
All supremacist religions, of course, teach that Universalism is wrong, misguided and/or evil.
But is it?
Is it really?
How different would our world be today if Universalism had been the guiding doctrine over the past couple of thousand years or more?