We believe in the God of the Bible. That’s it. Depending on the translation used, this God is called Yahweh or Jehovah, or is just referred to as “the Lord.” Most folks know that the difference between a Jew and a Christian is that a real Christian believes that Jesus was the Messiah that the Jews awaited. So we believe that Jesus was the Messiah that that Jews were waiting for and that there is a straight line from the first book of the Bible to the last. Most Christians view Christianity as a “fulfillment” of Judaism.
A Christian doesn’t believe in many gods, or any other god than the God of the Bible. We don’t believe, for example, that Allah is the same thing as the God the Bible, so we don’t believe that Allah is our God. Same for Krishna or Shiva. We don’t look to any other religious founder such as Buddha or Confucius. We believe that the God of the Bible is the true God, and that every other god is a false one.
This is partly because the Bible (also called the Scriptures) spells out that the God of the Old Testament is the one true God, and that there are no others. This was hard for the Jews to understand—that their “local” god, their national god, was also the God of the entire universe. Our problems today are similar—understanding that Christians believe that this one God is real, and that He is the only real one.