A large number of those people live in the Jewish nation of Israel. Over six million live in the United States. They believe in one God who created the universe and continues to care for it. That son died to accomplish this purpose. This is the same God that followers of Judaism worship.
Christians believe they can be delivered from sin through their belief in Jesus.
Christianity is divided into a number of individual denominations. The Roman Catholic Church is the largest Christian denomination with over a billion followers worldwide. People who believe these ideas are called Muslims. Parts of the Koran resemble the Christian Bible. It contains stories about the prophets who appear in the Old Testament and stories from the New Testament about Jesus.