By God, I assume that you are referring to the Christian or Judaic deity, since you believe in a monotheistic universe and invoke the Bible. If you are Christian in theological persuasion, then I assume you are a Western Christian, and not Coptic, Orthodox, or Syriac. Since you seem to read the Bible in literal sense, I gather you are from the denomination arising from Anabaptist faction.
If your query about many religions concerns the ever-increasing denominations of Christian factions in Western Christianity, just read some historical books regarding the Reformation because it is entirely a historical and cultural phenomenon with no real theological aspect to cloud perception.
As for extraterrestrial life forms, unless they profess a belief in a certain god-man who existed in a certain space-time in an insignificant planet, in an insignificant galaxy, if we do encounter an alien civilization, that will negate Judaism and Christianity.
Many, if not most, Christianity approach the Bible in a genre specific fashion. Genesis is in epic-poetic form, which means literal interpretation is likely to be entirely incorrect reading of Genesis. If you approach the Bible with the awareness of context and genre sensitivity, there is little conflict between belief and science.