Gospel v. Doctrine

I hear these word used seemingly interchangeably, so I wondered if there was a difference.

The Gospel mostly refers to the events of Christ's life: birth, ministry, death, burial, resurrection.

Doctrine is the rules for becoming more like Him.

They're not interchangeable, but they are intertwined. The more I read about what He said and did, the more I understand how to make doing and saying similar things a part of my life.

And, with practice, as perfectly natural a part of my life as breathing.