Doctrine is a set of beliefs.
Christian doctrine would be those beliefs that are consistent with the teaching of Jesus and his disciples.
Incorrect doctrine (which could be a matter of interpretation) is called heresy; it is a false teaching.
Key verse about Doctrine: Watch your life and doctrine closely. Persevere in them, because if you do, you will save both yourself and your hearers (1 Timothy 4:16, NIV).
A lifelong student of the Bible, Peter DeHaan, PhD, wrote the 1,000-page website ABibleADay.com to encourage people to explore the Bible. His main blog and many books urge Christians to push past the status quo and reconsider how they practice their faith in every area of their lives.