The answer is by understanding this diagram. It was recently shared with me by my good friend and fellow pastor, Dave Argue. It is taken from John 14:6 where Jesus says, "I am the way, the truth, and the life".
The core truth of Christianity is that Jesus is Lord. He was with God in the beginning. He was God, became flesh, lived and died - rose again the third day - now seated at the right hand of God. (John 1:1-2, 14, Colossians 1:15-20, Philippians 2:6-11, Romans 10:9). Jesus was not just a teacher, but is Lord of the universe, the Savior of all people and Ruler of life. He is worth dying for.
The next circle is doctrine. This is a group of denominational formulations of faith. They are developed in the midst of Bible study and experience. Such things might include belief about water baptism, the Lord's Supper, Sabbath observance, original sin - to name a few. These are topics to debate.
The third circle is convictions. These are strongly held matters of private conscience, personal beliefs of what is a right lifestyle and behavior. These are for dialogue.
Dave Argue writes, "Hopefully as we understand truth in this way, we will die for what is central to our faith but not kill for what is not. We will debate heartily the formulations of doctrine, but not cease to love those whose doctrinal positions differ from ours. And we will remember that truth reaches to the outer circle too. How enriched we are by the dialogue that sharpens our convictions."