From Natasha Crain’s book:

“Five Biblically Based Essential Christian Doctrines

It would be great if the Bible explicitly stated, “Here’s how to define a Christian from now on,” but it never comes straight out and says that. In fact, the word Christian is used only three times in the whole New Testament (Acts 11: 26; 26: 28; 1 Peter 4: 16). Jesus’ followers were called Christians because their behavior, activities, and speech were like his. Though we might not have an official membership guide for the early Christian community, it’s not hard to create one. The Bible makes it clear that the first Christians held at least five essential beliefs, or doctrines:

1. One God: “To you it was shown, that you might know that the LORD is God; there is no other besides him” (Deuteronomy 4: 35; see also 6: 4; Exodus 20: 3; Isaiah 43: 10; 44: 6).

2. The Deity of Jesus: “Jesus said to them, ‘Truly, truly, I say to you, before Abraham was, I am’ ” (John 8: 58; note that this references Exodus 3: 14, where God refers to Himself as “I am”; see also John 10: 30; 20: 28; Philippians 2: 5-8; Colossians 2: 9).

3. The Resurrection: “If Christ has not been raised, then our preaching is in vain and your faith is in vain” (1 Corinthians 15: 14; see also 15: 17; John 2: 19-21).

4. Salvation by Grace: “By grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast” (Ephesians 2: 8-9; see also Romans 3: 20; Galatians 2: 21; 5: 4).

5. The Gospel: “I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures” (1 Corinthians 15: 3-4; see also Galatians 1: 8-9).

With these essential doctrines in hand, we can now see that several groups who call themselves Christian don’t adhere to the basic beliefs that define Christianity. For example, Jehovah’s Witnesses deny the deity of Jesus, His physical resurrection, and salvation by grace. Mormons deny there is only one God, that there is salvation by grace, and that Jesus is (uncreated) deity. Both groups hold beliefs contrary to the gospel given by Scripture. When we use essential doctrines to meaningfully define Christianity, it quickly becomes clear that major disagreements within “Christianity” are really major disagreements between Christianity and other religions.”

Source:  Crain, Natasha. Keeping Your Kids on God’s Side: 40 Conversations to Help Them Build a Lasting Faith (pp. 83-84). Harvest House Publishers. Kindle Edition.