There are dozens of Bible verses directing us to Know God, to learn and draw close to Him. Intimacy with God comes through prayer and reading the Bible. The Bible is the literal Word of God and as such to live the Christian life to the fullest we have to know what it says.
Another reason we need to know what we believe when we claim to be a Christian is written about by Peter. In 1 Peter 3:15 it says
“But in your hearts revere Christ as Lord. Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect.”
So, in order to give an answer to some questions we might be asked we have to know what the Bible teaches, know doctrine and be able to give an answer. Answering these questions has been lumped under the topic of apologetics.
Apologetics isn’t the art of apologizing for our faith. No, it means to explain why something is true and defending that truth. There are many categories of questions and many answers have been developed through this process of defining Christian belief. The link below is an excellent overview on this topic. If you are interested in learning more about defending your faith in Christ some of the best and easiest books to read and understand are written by Lee Strobel. With these books you can have a better understanding of the many aspects of Christianity, Christ and Faith.