What we do in this current life has an eternal impact. The New Testament insists on the decisiveness of this life. In the early church, the “idea that the coming judgment will be based on deeds done in this life was widespread.” For example, “Do not fear those who kill the body but cannot kill the soul. Rather fear him who can destroy both soul and body in hell” (Matt. 10:28).
All through Scripture it talks about the Day of the LORD (sg.). The Bible does not talk about judgments starting at the Great White Throne Judgment (Rev. 20:11ff) and going from there on into eternity where people have multiple chances to repent. That’s why it says, “Behold [ἰδοὺ], now [νῦν] is the day of salvation” (2 Cor. 6:2; cf. Ps. 32:6; Is. 55:6). Acts 17:31 says, God “has fixed a day [sg.] on which He will judge the world in righteousness by a man whom He has appointed; and of this He has given assurance to all by raising Him [i.e. Jesus] from the dead.”
Hebrews says, “it is appointed for man to die once, and after that comes judgment [sg.]” (9:27). Thus, in Scripture, we do not see that people can repent after the Judgment. Actually, to get the idea of repentance after the Judgment you would have to add to Scripture. Yet, listen to Revelation: “I warn everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues described in this book, and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book” (22:18-19).
Also recall that it is those who “conquer” in space and time who can eat from the tree of life and who will not be touched by the second death (Rev. 2:7, 11). It’s the one who conquers on earth before the Final Judgment that has a “white stone” as admission to heaven (2:17). So we see in Revelation that there is a clear and decisive end to the chance that people have to repent. The one who conquers is the one “who keeps my works until the end” (v. 26). It is those who conquer on earth before the coming of the Lord Jesus who will be dressed in white garments and have their names in the book of life (3:5).
Jesus warns of the “thief that comes in the night” (e.g. Lk. 12:39-40; cf. 1 Thess. 5:2; 2 Pet. 3:10). Jesus is mercifully warning people to turn to Him now, before it is too late. We are exhorted to be ready and live a certain way because the way we live has, in a very real sense, an infinite impact. Many of the moral imperatives in Scripture show us the importance of our decisions here because what we do and don’t do has an eternal impact.
What we do in space and time (cf. Eccl. 12:13-14; Matt. 11:20-24; Lk. 12:48; 20:47; Rom. 2:6) and whether we believe the gospel and turn to the Lord in repentance has eternal significance. We see this truth attested throughout Scripture. For instance, Jesus said, “We must work the works of Him who sent me while it is day; night is coming, when no one can work” (Jn. 9:4). “Death is coming, which will be the setting of the sun, and the end of this day; after which no work will remain, nothing to be done of any significance in order to the obtaining of the recompence of eternal significance.”
We see the decisiveness of this life through Matthew 25. In the words of Augustus Hopkins Strong, Matthew 25 shows us that
All nations—all the Gentiles—are gathered before the King; and their destiny is determined, not by their conscious acceptance or rejection of the historical Savior, but by their unconscious acceptance or rejection of him in the persons of those who needed services of love… This does not square with the idea of a future probation. It rather tells us plainly that men may do things of final and decisive import in this life, even if Christ is unknown to them… The real argument against future probation is that it depreciates the present life, and denies the infinite significance that, under all conditions, essentially and inevitably belongs to the actions of a self-conscious moral being.
Strong goes on to say:
In reference to man and his existence, the Scriptures speak of two and only two aiones or ages: one finite and one infinite, one limited and one endless, the latter succeeding the former…
The two aeons, or ages, known in Scripture, are mentioned together in Matt. 12:32, ‘It shall not be forgiven him, neither in this world (aion), nor in the world (aion) to come;’ in Mark 10:30, ‘He shall receive an hundredfold now in this time (kairos), and in the world (aion) to come, eternal life;’ in Luke 18:30, ‘He shall receive manifold more in this present time (kairos), and in the world (aion) to come, life everlasting;’ in Eph. 1:21, ‘Above every name that is named, not only in this world (aion), but also in that which is to come.’ The ‘things present and the ‘things to come,’ mentioned in Rom. 8:38; 1 Cor. 3:22, refer to the same two ages. These two aeons, or ages, correspond to the two durations of ‘time’ and ‘eternity,’ in the common use of these terms. The present age, or aeon, is ‘time;’ the future age, or aeon, is ‘eternity.’
What we do matters. Indeed it matters forever. The Bible insists on the decisiveness of this life.
 Packer, Celebrating the Saving Work of God, 178.
 Allison, Historical Theology, 703.
 The International Standard Bible Encyclopedia says the Day of the LORD
“in the OT, the future consummation of the kingdom of God and the absolute cessation of all attacks upon it (Isa. 2:12; 13:6, 9; 34:8; Ezk. 13:5; 30:3; Joel 1:15; 2:11; Am. 5:18; Zeph. 1:14; Zec. 14:1). It is a ‘day of visitation’ (Isa. 10:3), a day ‘of the wrath of the Lord’ (Ezk. 7:19), a ‘great day of the Lord’ (Zeph. 1:14). The entire conception in the OT is dark and foreboding.
On the other hand the NT idea is pervaded with the elements of hope and joy and victory. In the NT it is eminently the day of Christ, the day of His coming in the glory of His Father. The very conception of Him as the “Son of man” points to this day; e.g., Jn. 5:27 says that the Father ‘has given him authority to execute judgment, because he is the Son of man’ (cf. Mt. 24:27, 30; Lk. 12:8). In the NT also, however, there is a dark background to the bright picture, for it still remains a ‘day of wrath’ (Rom. 2:5f.), a ‘great day’ (Rev. 6:17; Jude 6), a ‘day of God’ (2 Pet. 3:12), a ‘day of judgment’ (Mt. 10:15; 2 Pet. 3:7; Rom. 2:16)…
To the unbeliever, the NT depicts it [i.e. the day of the LORD] as a day of terror; to the believer, as a day of joy” (H.E. Dosker, “Day of the LORD,” 879).
 Edwards, 517.