You must simply ask Him. I was an atheist, but at my lowest point, Jesus came to me.

As far as the Abrahamic God goes, the Christians have the best historical support, assuming you believe in one almighty God. Jesus Christ fulfilled the Jewish prophecies, and the Muslims plainly contradict the tradition. The logical monotheist must be Christian. The Tanakh ignores the Messiah, and the Quran contradicts itself.

All other polytheistic traditions lead to God as well. They have reincarnation, where you reincarnate until you can become one with all things, this is essentially God, but it is missing out on His commands