John 3:3-5 says that there is only one way to enter the Kingdom of God. It is necessary, according to the Lord Jesus, to be born from above by the Holy Spirit in order to enter — or even see — the Kingdom of God. He emphasized the absolute truth of His statement saying, “Amen, amen” or “Truly, truly.” He went on to tell how to be born again — by believing in the Son of God. The structure of Jesus’ statement asserts the necessity of believing in Jesus to enter God’s Kingdom, but says nothing of the sufficiency of it.
Is believing enough? It depends. In John 3:15-18, Jesus does say that believing in Him is sufficient to escape the condemnation of everlasting fire. But He does not say that believing in Him is necessary to escape the lake of fire, which should be of great comfort to anyone who has lost an infant. We must consider the possibility that — as most Christians assume — entering God’s Kingdom is equivalent to the escaping condemnation in the lake of fire; and that the two concepts are two sides of the same coin – that you can’t have one without the other. If that were true, then it would be impossible for children having died before being able to understand and believe the gospel to enter the Kingdom of God, and therefore they would be destined for the lake of fire.
The scriptural argument against this assumption is: Paul wrote that no one can call Jesus “Lord” without the Holy Spirit. (1 Corinthians 12:3) But Jesus said that not everyone who addresses Him as “Lord, Lord” will enter the Kingdom of Heaven. (Matthew 7:21) Isn’t this a contradiction? Also the New and Old Testament both state that whoever shall call on the name of the Lord shall be saved. (Joel 2:32; Romans 10:13)
Is it possible to be saved and not be in the Kingdom of God? The Bible says so. But how can this be? Here is the secret to understanding all the mysteries of the Bible: Salvation in eternity is not the same thing as entrance into the Millennial Kingdom. At some point in the future, Jesus Christ will return to this earth to set up His Kingdom which will last 1000 years, which will be followed by eternity. This distinction is either downplayed, or even the denied outright, in most churches.
The Bible seems to describe no less than two salvations. When a certain jailer asks Paul the apostle “What must I do to be saved?” Paul replies, “Believe on the Lord Jesus Christ and thou shalt be saved.” (Acts 16:30-31) Sounds easy! But when asked if many or few will be saved, Jesus tells his disciples to “strive to enter in at the narrow gate, many seek it, but few find it.” (Luke 13:24) So, is it “believe”, or “strive”? Do you have to strive, (agonize, struggle, wrestle, labor) in order to believe? Or do you have to believe in order to strive? It seems that the latter is more likely, and agrees more with the gospel of grace. You must first believe in the Son of God to be saved, and having become a child of God, and having access to the Father, you are enabled and empowered to strive toward the goal of entrance into the Millennial Kingdom.
And what if you don’t strive? There is no guarantee of Kingdom entrance for the believer, only of escaping the punishment of the lake of fire. What will the believer that does not enter the Kingdom do for the duration of the thousand-year reign of Christ? Search the scriptures! Matthew records it as darkness. “Many are the called, but few are the chosen.” (Matthew 20:16)
You ask, what must I do to enter the Kingdom, then? I can’t tell you. If I did, it would immediately become legalism. Read your Bible, every word. Abide in Jesus and his words and let them abide in you. (John 15:7) Walk in the spirit. (Galatians 5:16) Forgive others and confess your sins regularly. (Matthew 6:14-15; 1 John 1:9) Love, practice mercy, obey God and His word. (Zechariah 7:9) The good thing is, even the smallest act of kindness done in the Lord’s name will be repaid in His Kingdom. (Matthew 10:42) So be confident that your good works will abide and be assured that you are saved eternally no matter what, if you have trusted Christ as savior.