Christians disagree about a lot. That's why you see so many different churches.
There are a few basic Christian beliefs, however — points that most, but not all, Christians can agree on.
Basic Christian beliefs begin with the Bible, particularly the New Testament, which makes up the last two-thirds or so of the Bible. Christians have different ways of approaching the Bible. Some take it literally and even believe God dictated the Bible to the people who wrote it down. Others believe the Bible was written by humans and to specific people and applies mainly to their place and time. No matter how literally they take the Bible, all Christians consider it important. It tells the story of Jesus, the founder of the Christian faith, and the story of the first community of Christians, the first church. It also includes letters from leaders of the first churches explaining how to live a Christian life.
Jesus is the center of the Christian faith. He was a Jewish teacher who was likely born around 3 B.C.E. The exact date isn't known. Some Christians emphasize Jesus' teachings, while others see his death and resurrection as more important, but all Christians recognize Jesus. Most Christians believe Jesus was both God and human. If this sounds confusing to you, you're not alone. Christians have been trying to explain this concept for two millennia. Many Christians believe Jesus' mother was a virgin, a miracle that came from God. Some Christians believe that is a story that developed about Jesus. Regardless, all Christians believe Jesus was special. The Bible asserts that Jesus lived a perfect life, and Christians try to follow his example.
Jesus set out two big commandments: Love God and love your neighbor. His definition of neighbor wasn't the person who lives next door, though. By "neighbor," he really meant everyone. He told his followers to love their enemies. So Christians believe they are supposed to love God and all people. So how is it they fought the Crusades? Good question.
Jesus also told his followers to "make disciples of all the nations." Christians have a mandate to share their faith. Most don't think that means forcing people, but throughout history, many have.
Christians believe Jesus saves them. That means a lot of different things to different people, but Christians don't believe they're good enough on their own, and they don't think they can ever get there. This is what separates Christianity from most other religions. Paul, one of the early Christian leaders who wrote much of the New Testament, explains that if someone does anything wrong, they're guilty of breaking the whole law. That applies to everyone. The punishment for this, he says, is death. Because Jesus was perfect, he died in the place of everyone. This is called "substitutionary atonement," but you probably don't need to know that. Most Christians believe God sent Jesus to die so people who follow him could be saved from hell.
Not all Christians believe this, but they all take Jesus' death seriously. It shows that God is willing to sacrifice everything to have a relationship with people.
Christians believe they should do good things, like feeding the hungry, giving clothes to people who need them, and taking care of people who are alone. They don't think this earns them a ticket to heaven, but they do it because they are grateful that Jesus died for them.