I do not believe in jesus, but I can assure you, I am doing my best to be a good person with the knowledge that I have. I try to respect others and to treat them as I would like to be treated.
But how come I don't know God ?
I don't know you so I can't put words in your mouth as to why you don't know God. I know this much though: That some people have not because they ask not. Seek, and you will find. Knock, and the door will be opened. Have you asked Him to reveal Himself to you?
There is no magic formula for knowing God because He comes to us all differently. But I know that He didn't come to me until I asked Him to. And when He revealed Himself to me, it wasn't in my timing, but His. What I mean is, if you pray to God to reveal Himself, He may come to you in some profound way that moment. He may come to you a week later- a month - a year. Seek and you'll find.
"A man can no more diminish God's glory by refusing to worship Him than a lunatic can put out the sun by scribbling the word, 'darkness' on the walls of his cell." -C.S. Lewis