Q: “Will people have to repent to be saved during the Millennial reign of Christ?”
A: This is a good question. It is clear that through the past and the present dispensations the main cry was for people to repent, confess of their sins through open confession (New Testament) or sacrifice (Old Testament) and turn from their wicked ways and face God. Repentance is all about turning from the wrong way in which a person is walking to turn to God in humility and faith with the intent of doing right in order to please Him.
However, the Millennium will be a different situation. In this present age Satan is busy using his devices of repackaged lies, grave seduction, and lust to lead man away from God into the slippery-slide of rebellion, depravity, and spiritual ruin, while Jesus will be ruling as the Prince of Peace during the next dispensation to the point even a child will be at peace with the beasts of the fields (Isaiah 11:6-8).
During the next age to come, Satan will be bound for a thousand years, which means that he will not be around to tempt man and thwart Jesus’ ways of righteousness as the knowledge and the glory of the Lord will fill the earth, silencing man from claiming ignorance and walking in foolishness towards the things of God (Psalm 72:19; Isaiah 11:6-9; Habakkuk 2:14; Revelation 20:2, 7).
Remember what Jesus said to “doubting” Thomas, “Thomas, because thou hast seen me, thou hast believed: blessed are they that have not seen, and yet have believed” (John 20:29). In this age we are saved by grace through faith in Christ and His work of redemption but there will be no debate during the Millennium as to whether Jesus lives and who He is for He will be literally sitting on the throne as King, High Priest, and Judge. There will be no temptation to do wrong and no persuasion to be contrary because the temptation will be alleviated.
We are told that Jesus will rule with a rod of iron and those leaders who do not come to Jerusalem during the Feast of the Tabernacles will bring drought upon their countries (Zechariah 14:16-17; Revelation 12:5). Clearly, Jesus will be reigning as a just Judge, which means that consequences will be measured out in fairness in relationship to any rebellion. Such judgment will ensure order and harmony.
I can only speculate because the Bible does not come out and say man will have to repent to be saved during this thousand-year period. However, it is clear that in this dispensation man needs to obey the King of kings. In our present age, we obey out of faith towards God and in expectation of promises yet to come. We believe what He says in His Word, walk in obedience as a result, which causes genuine faith to walk hand in hand with love (Galatians 5:6). In the future age, man will obey because of fear of consequences or out of love for the Lord. Jesus said it best, “If you love me, obey me,” and “Why call me Lord when you do not obey me” (John 14:15; Luke 6:46)? Even though man desires peace, it becomes clear that it is godly love that will transform the inward character of man to be true to the Lord and His righteousness, regardless of the age and dispensation. Keep in mind, love and acceptable obedience is a personal choice. Love ensures the right motive and obedience sustaining character.
If man does not develop a love for the Lord, then when Satan is loose again, those who refuse to be ruled by godly love and lasting peace will be open once again to be taken down the slippery path of utter spiritual ruin by the true enemy of their souls.