Here you go, straight from the dictionary's pages. Couldn't you have just looked it up?
glad tidings; especially, the good news concerning Christ, the Kingdom of God, and salvation
one of the four narratives of the life and death of Jesus Christ, written by Matthew, Mark, Luke, and John
a selection from one of the gospels, for use in a religious service; as, the gospel for the day
any system of religious doctrine; sometimes, any system of political doctrine or social philosophy; as, this political gospel
anything propounded or accepted as infallibly true; as, they took his words for gospel
accordant with, or relating to, the gospel; evangelical; as, gospel righteousness
to instruct in the gospel