Not sure how you can know someone when you have no reason to believe they exist. How does that work?
The greatest Commandment is to love God above all else. Struggling with this over the years my question was how can I love someone I don't even know? The Christian answer was to know Jesus is to know God. I think that may work for many, but I still struggled. Then I came across a Jewish philosophy. Knowing and loving God's Law teaches one to know and love God. This still took a lot of time (years), but I kept at it. In the end it was what worked best for me. Still, I had no trouble believing in God, so I that was not a step I had to overcome. Perhaps belief will come with knowing the Law? But first and primary, Do you want to believe in God?
It seems to me that if someone has no wish to know God, to love God, or to believe in God it is a long, hard row to hoe for something that is not even wanted.