You said beliefs don't alter reality. Some beliefs ARE reality.
Unless you can prove otherwise (there is the burden of proof argument, which I have too much of a headache and probably not the patience to go into .....)
Of course we live in the world, but to a Christian, everything in the world is based on the existence of God who created the world and all that is in it.
Any atheist doesn't even consider God. They don't believe.
Of course, there are the multitude of others that have their own "version" of God they believe in, or, Creator if you rather....
No, beliefs are not reality. You can't will a reality into being, you can only fool yourself. Atheists have a belief too, they just don't want to admit it. I don't believe any man made versions of God. I don't know and have no problem being honest about it. Christians claim their beliefs are fact but it's a faith. That's the main problem with it, religion forces you to be dishonest with yourself.
That, in and of itself, is an opinion.
Depth of though and openness of mind will reveal that anything is possible and we are limited in our comprehension.
That any person could be right or wrong, and, that we are all fallible and no one (no human being) knows any absolute truth -
unless the One that DOES - the One that has omniscience/omnipotence and is omnipresent - reveals it to them.