Almost every Christian makes some distinction between essentials of the faith and non-essentials. The distinction itself is fairly uncontroversial. But what exactly are the essentials? That's a bit tougher.
There are a number of ways to answer that question. We could look at church history and what God's people have always believed. We could look at the ancient creeds and confessions of the church. We could look at the biggest themes of Scripture (e.g., covenant, love, glory, atonement) and the most important passages (e.g., Genesis 1, Exodus 20, Matthew 5-7, John 3, Romans 8). I want to take a little different route and consider what are the behaviors and beliefs without which Scripture say we are not saved. These are not requirement we must meet in order to save ourselves and earn God's favor. Rather these are the essential beliefs and behaviors that will be manifest in the true Christian.
I don't pretend that this is anywhere close to a comprehensive list from the Bible. But a list like this may be helpful in guarding against false teaching and examining our own lives.
Ten Essential Christian Behaviors
1. We repent and turn from our sins (Matt. 5:29-30; 11:20-24; Acts 2:38; 3:19; Heb. 10:26-27).
2. We forgive others (Matt. 6:14-15; 18:33-35).
3. We are undivided in our devotion to God and to Jesus Christ (Matt. 6:24; 10:38-39; 19:16-30; John 12:24-26).
4. We publicly acknowledge Jesus before others (Matt. 10:32-33; 21:33-44; 22:1-14; 26:24; John 5:23)
5. We obey God's commands and do not make a practice of sinning (John 14:15; 1 John 3:9-10; 1 John 5:2).
6. We live a life that is fruitful and not fleshly (Matt. 12:33-37; 21:43; 24:36-51; 25:1-46; Gal. 5:18-24; 6:5; Heb 13:4; 1 Cor. 6:9-10).
7. We are humble and broken-hearted for our sin (Matt. 5:3; 18:3-4; 1 John 1:8-10).
8. We love God and love others (Matt. 22:34-40; John 11:35; 15:12; 1 Cor. 13:1-3; 1 John 3:14-15).
9. We must persevere in the faith (Heb. 6:4-6; 10:29-31; 12:12-17; 1 Cor. 9:24-27; 1 Tim. 5:11-12).
10. We help our natural family and church family when there are physical needs (1 Tim. 5:8; 6:18-19; 1 John 3:17).
Ten Essential Christian Beliefs
1. We must be born again by the Spirit of God (John 3:5).
2. Jesus is the Christ, the Son of God (John 3:18, 36; 6:35, 40, 47, 53-58; 8:19, 24; 11:25-26; 12:48; 14:6; 15:23; 20:30-31; Gal. 3:7-9).
3. The benefits of the gospel come by faith, not by works of the law (Acts 15:8-11; Gal. 1:6-9; 2:16, 21; 3:10-12, 22).
4. Salvation comes from Jesus Christ, our faithful high priest, the radiance of God's glory and our brother in the flesh (Col. 1:15-23; Heb. 2:4).
5. God exists and rewards those who seek him (Heb. 11:6, 16).
6. We are saved by Jesus Christ and him crucified (1 Cor. 1:18).
7. The good news of the gospel is 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, and he appeared to many witnesses (1 Cor. 15:1-11).
8. Jesus Christ was bodily resurrected and our bodies will be resurrected (1 Cor. 15:12-19).
9. Jesus was manifested in the flesh, vindicated by the Spirit, seen by angels, proclaimed among the nations, believed on in the world, taken up in glory (1 Tim. 3:16; 1:3, 18-20; 6:3-4, 20-21).
10. God saved us and called us to a holy calling, not because of our works but because of his own purpose and grace, which he gave us in Christ Jesus before the ages began, and which now has been manifested through the appearing of our Savior Jesus Christ, who abolished death and brought life and immortality to light through the gospel (2 Tim. 1:8-14).
You could multiply lists like this tenfold. The point is not to be exhaustive, but to show by way of example just how many things the Bible considers to be essential and how precious these truths should be to the Christian. There are a number of behaviors in Scripture which serve to prove or disprove our Christian commitment. Likewise, there are a number of beliefs in Scripture without which we cannot be saved and which must be true if salvation is even possible. We would do well to study these beliefs and behaviors, embrace them, and promote and protect them with our fullest zeal and efforts.