Many religious people who think they are saved are deceiving themselves. Jesus said, "Not everyone who says to Me, 'Lord, Lord,' shall enter the kingdom of heaven, but he who does the will of My Father in heaven. "Many will say to Me in that day, 'Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?' And then I will declare to them, 'I never knew you; depart from Me, you who practice lawlessness!'" (Matthew 7:21-23)
There will be people who profess that Jesus Christ is Lord and do great things in His name only to discover at their judgment that this did not qualify them for eternal life. For all outward appearances in the world, these people look like they are among the saved. Indeed, most people in the world believe salvation to be a matter of earning it through being a good person. Even many who claim to trust in Jesus say that this faith is not enough by itself, that you must do something to deserve being saved.
Matthew 7:23 gives the key to the difference between people who do good works to be saved and those who do good works because they are saved: Jesus "never knew" those who never trusted in Him alone. As Creator-God, Jesus certainly knows who the unsaved are but He doesn't know them in the sense of having a relationship with them.
For there to be any real relationship between people as well as with God, some sort of interaction must take place. Believers find God speaking to them through His Word the Bible and we speak to Him in prayer. If this fellowship is not taking place, one should ask themselves if they are really saved: "If we say that we have fellowship with Him, and walk in darkness, we lie and do not practice the truth" (1 John 1:6).
Jesus made all the overtures necessary to make a relationship with God possible when He paid the penalty for the sins of those who believe Him. All we do to have everlasting life is respond to Him by receiving His gift to us: "For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life" (John 3:16).
John 3:16 only says that we must believe, it doesn't say there is any other thing one must do to have eternal life. The futility of working to earn Gods favor is explicitly stated in Ephesians 2:8-9: "For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast." This passage makes it clear that even our faith to believe is a gift from God. Since there is nothing we can do ourselves to earn salvation, we can't boast about "our achievement."
The thief who died on the cross next to Jesus (Luke 23:39-43) certainly did not have an opportunity to do any good works to earn salvation. All he did was trust in Jesus, publicly acknowledge that He was Lord, and ask for salvation. The man had no chance to be baptized, go to church, tithe, or do anything else yet Jesus knew his heart and promised, "today you will be with Me in Paradise."
Receiving eternal life is so simple, most people reject the idea that all they need to do is trust in Jesus to be saved from hell. So men invent their own ways of salvation seeking to be in control of their eternal destiny and satisfying their desire for pride through self-accomplishment: "There is a way that seems right to a man, but its end is the way of death" (Proverbs 14:12).
All the religions of the world are the same in that they make the practice of a set of ordinances or a particular lifestyle a requirement for salvation. But God's standard is perfection (Matthew 5:48) so outside His provision, "all our righteousnesses are like filthy rags" (Isaiah 64:6). True Christianity is not a religion, it is a relationship.
People reject the simplicity of faith in Christ alone because they don't see the value of good works if they do not count for salvation. Christians strive to be good people out of obedience to the Lord. This is why God saved us: "For we are His workmanship, created in Christ Jesus for good works" (Ephesians 2:10). God knows the intents of our heart (Hebrews 4:12). The proper motivation is what makes works good in God's eyes. Things done to glorify God out of gratitude for His saving us is the right motivation. The wrong motivation is to think that you are earning God's favor.
How arrogant of men to reject the authority of their Creator by striving to be their own savior. Those who think they can earn anything from God attempt to reverse their role with Him and make Him obligated to respond to them. To think you can make God indebted to you is rebellion against Him.
Thank God we don't have to depend on our own performance to have eternal life! Jesus paid the penalty for the sins of those who believe in Him, "God demonstrates His own love toward us, in that while we were still sinners, Christ died for us" (Romans 5:8). Believing is more than acknowledging the historical facts about Jesus, it is trusting that God accepts the sacrifice of His Son on the cross as full payment for your sin.