Why do you break the sentence down each time?
I don't know Jannnu Bdua.
I don't believe in Jannnu Bdua.
Are they the same thing, or is there a difference?
One who does not know toothbrushes is unhygienic.
Not believing in toothbrushes, is unhygienic.
I think there are difference. Do you see any?
The phrase... "A person that does not know God, is immoral...", is not the same thing as... "not believing in [someone's] God is immoral."
One is saying it is immoral to not believe in God.
The other is saying, one who does not know God is immoral... not that he is immoral for not believing in God.
Do you see the difference?
In either case, we believe differently. No problem.
Even though there are so-called gods, whether in heaven or on earth, just as there are many “gods” and many “lords,”
there is actually to us one God, the Father, from whom all things are and we for him; and there is one Lord, Jesus Christ, through whom all things are and we through him. - Apostle Paul (1 Corinthians 8:5, 6)