Is it the fault of a loving God that those with warped beliefs are believing the wrong thing?
Adam and Eve apparently believed the wrong thing about God and the reason why there were not to eat of the fruit of the tree of life. Or, at least they doubted. Is it surprising then, that other people would do the same? Did that happen because God didn’t love them? He created the universe, Earth and the garden for them. He visited with them personally every day. That would seem to be pretty good evidence that He really cared for them. He gave them the freedom to choose. Not some artificial thing (such as elections in Russia, China or North Korea), but genuine freedom, allowing them to choose something other than Himself. Of course, without that, choosing Him wouldn’t mean much.
Is it possible to know what the truth is so that we can know that we are believing in the right thing?
This requires God revealing Himself to us. And, He has done so, through creation (Romans 1:19,20; Psalm 19), Jesus Christ (Hebrews 1:2), prophets (Hebrews 1:1) and closely related to that, the Scriptures (2 Peter 1:20,21).