Many people have the idea that if they do enough good, or don't do too much bad, then God will allow them to enter heaven. In other words, when it comes to obtaining eternal life, they think God grades on a curve. This assumption is built on some erroneous thinking.
First, this way of thinking does not understand that God's standard of goodness is absolute. If someone could obtain eternal life by being good, by keeping God's laws, or by making any kind of commitment, then his or her performance would have to be perfectly good as God is perfectly good. Jesus Christ taught that no one is absolutely good but God (Matt. 19:17; Rom. 3:9-12). Many people have a relative concept of goodness, that is, they look at others to see how their own goodness compares. Of course, they find that they are better than some and worse than others. But other people are not the standard of heaven; God Himself is.
Second, it is a mistake to think that man's best is good enough. The Bible teaches that a person's best efforts to obtain eternal life are not worthy of God's acceptance (Isa. 64:6; Rom. 3:20; Eph. 2:8-9). A person would have to keep God's standards (as reflected in His laws) perfectly and could not fall short of even one aspect or command (Gal. 3:10; James 2:10). There is always room to do better or to be more committed, so even one's best performance is not good enough.
Third, it is a mistake to think that man's problem is simply his conduct. No one can obtain eternal life by outward behavior, but only by believing in Jesus as Savior from sin. The Bible teaches that sin, not sins per se, keeps unsaved people from experiencing God's life. Sins are the result of a sinful condition, much like a cough and runny nose are the result of a cold. While we might treat the symptom of the problem (the cough), the cure must deal with the cause or condition (the cold). Unsaved man's problem is first his sinful spiritual condition in which he is dead to God (Rom. 3:18; Eph. 2:1). Thus changing or improving one's conduct does not deal with the problem that keeps an unsaved person from having eternal life and entering heaven.
Fourth, it is a mistake to ignore what God has already done for us. God sent His Son, Jesus Christ, to do what no other person could do. Since every unsaved person's efforts to do good or be good are tainted by sinfulness, someone had to satisfy God's demand for justice on each person's behalf. Only Jesus could do this, because as God the Son He was without sin and perfectly acceptable to God. Jesus took every person's sin upon Himself and paid the price of death for all (2 Cor. 5:21). Then he offered everyone the gift of eternal life, which can be received through faith (John 1:12; 3:16; Eph. 2:8-9). To think that we must perform something insults God and His perfect gift as inadequate.
No one can hope to have eternal life by being better than others or by being good enough. No one's works, law keeping, performance, commitment, reformation, repentance from sins, abstinence from sin, baptism, church attendance, sincerity, or good intentions is good enough for heaven. The only hope is to accept what God has already done by believing in Jesus for eternal life. If eternal life comes from what He did and not from what anyone does, then no one can do anything to become acceptable to God.
Salvation by grace means that eternal life does not come by human effort or performance; it is a gift from God. Through Jesus Christ, God accomplished everything necessary for anyone to have eternal life. Only those who believe His promise and therefore receive His life will enter heaven.