Judgement day is when all people who are not already in heaven will be judged.
However, as this particular question is vague regarding both who these people are [does it refer to All people? Christian? non-christian? Those alive? Dead?] and when it occurs, and in the Question History previous versions of this question "...asked ...and said it was the same as ...." when they were actually different questions, there are several answers depending on what was actually meant.
(i)
Just being a good person is not enough to get into heaven: it is essential this is understood. Only God is good:
The young ruler was rich and law-abiding but that didn't qualify him for entry into heaven:-
Matthew 19:16-26
16 Now behold, one came and said to Him, "GoodTeacher, what good thing shall I do that I may have eternal life?"
17 So He said to him, "Why do you call Me good? No one is good but One, that is, God. But if you want to enter into life, keep the commandments."
18 He said to Him, "Which ones?"
Jesus said, "'You shall not murder,' 'You shall not commit adultery,' 'You shall not steal,' 'You shall not bear false witness,'19 'Honor your father and your mother,' and, 'You shall love your neighbor as yourself.' "
20 The young man said to Him, "All these things I have kept from my youth. What do I still lack?"
21 Jesus said to him, "If you want to be perfect, go, sell what you have and give to the poor, and you will have treasure in heaven; and come, follow Me."
22 But when the young man heard that saying, he went away sorrowful, for he had great possessions.
23 Then Jesus said to His disciples, "Assuredly, I say to you that it is hard for a rich man to enter the kingdom of heaven.24 And again I say to you, it is easier for a camel to go through the eye of a needle than for a rich man to enter the kingdom of God."
25 When His disciples heard it, they were greatly astonished, saying, "Who then can be saved?"
26 But Jesus looked at them and said to them, "With men this is impossible, but with God all things are possible."
Just being non-evil or good results in spiritual death: repentance is essential to avoid this spiritual death:-
Luke 13:1-6
v. 1 There were present at that season some who told Him about the Galileans whose blood Pilate had mingled with their sacrifices.2 And Jesus answered and said to them, "Do you suppose that these Galileans were worse sinners than all other Galileans, because they suffered such things?3 I tell you, no; but unless you repent you will all likewise perish.4 Or those eighteen on whom the tower in Siloam fell and killed them, do you think that they were worse sinners than all other men who dwelt in Jerusalem?5 I tell you, no; but unless you repent you will all likewise perish."
Repentance is obligatory
Acts 2:36-38, 40-42, 44-47:-
36 "Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ." 37 Now when they heard this, they were cut to the heart, and said to Peter and the rest of the apostles, "Men and brethren, what shall we do?" 38 Then Peter said to them, "Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit. 40 And with many other words he testified and exhorted them, saying, "Be saved from this perverse generation."41 Then those who gladly received his word were baptized; ...42 And they continued steadfastly in the apostles' doctrine and fellowship, in the breaking of bread, and in prayers....44 Now all who believed were together, and had all things in common,45 and sold their possessions and goods, and divided them among all, as anyone had need. 46 So continuing daily with one accord in the temple, and breaking bread from house to house, they ate their food with gladness and simplicity of heart,47 praising God and having favor with all the people. And the Lord added to the church daily those who were being saved.
Sin results in death, while accepting Christ results in eternal life:-
Romans 6:22-23:-
22 But now having been set free from sin, and having become slaves of God, you have your fruit to holiness, and the end, everlasting life.23 For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.
Christians are repentant sinners who have accepted Jesus Christ as Saviour and been forgiven:-
Romans 3:23-26, 28:-
23 for all have sinned and fall short of the glory of God,24 being justified freely by His grace through the redemption that is in Christ Jesus,25 whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed,26 to demonstrate at the present time His righteousness, that He might be just and the justifier of the one who has faith in Jesus [ie Christians].
28 Therefore we conclude that a man is justified by faith apart from the deeds of the law.
In answer to the question "How good do I have to be to go to heaven?" John MacArthur says:
"Most people understand that doing evil can keep us out of heaven. But few realize the Bible also teaches that doing good cannot get us in. None of us could ever gain enough merit to deserve heaven. We are sinful, and God's standard is utter perfection. Jesus said, "Unless your righteousness exceeds the righteousness of the scribes and Pharisees, you will by no means enter the kingdom of heaven" . He added, "you are to be perfect, as your heavenly Father is perfect......"
(see www.gty.org/Resources/Questions/Christian+Living/Heaven)
(ii) If this question is referring to the sudden spiriting away, or vanishing, or disappearance, of all true Christians [ie perhaps not C.I.N.O. christians (Christians In Name Only)] still living on Earth, then this is known as the Rapture of the church:-
Joh 14:1-3 MKJV Let not your heart be troubled. You believe in God, believe also in Me. (v.2) In My Father's house are many mansions; if it were not so, I would have told you. I go to prepare a place for you. (v.3) And if I go and prepare a place for you, I will come again and receive you to Myself, so that where I am, you may be also.
1Thessalonians 4:15-17:-
15 For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord, will not precede those who have fallen asleep [ie died].16 For the Lord Himself will descend from heaven with a shout, with the voice of the archangel and with the trumpet of God, and the dead in Christ will rise first.17 Then we who are alive and remain will be caught up together with them in the clouds to meet the Lord in the air, and so we shall always be with the Lord.18 Therefore comfort one another with these words.
1Co 15:51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, (v.52) In a moment, in the twinkling of an eye, at the last trump : for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.
[Note:in his Study Bible notes on this verse (p.1817) John MacArthur says this 'last trump' is not one of the Judgement Trumpets in Revelation 8-11.]
(iii)
If this question is not meaning the Rapture, then it would probably be referring to the Bema Seat Judgement of Christ which is evaluates and rewards Christians their stewardship during their earthly life:-
Rom 14:10-12 MKJV But why do you judge your brother? Or also why do you despise your brother? For all shall stand before the judgment seat of Christ. (v.11) For it is written, "As I live, says the Lord, every knee shall bow to Me, and every tongue shall confess to God." (v.12) So then each one of us will give account concerning himself to God.
1Co 3:13-15 MKJV each one's work shall be revealed. For the Day shall declare it, because it shall be revealed by fire; and the fire shall try each one's work as to what kind it is. (v.14) If anyone's work which he built remains, he shall receive a reward. (v.15) If anyone's work shall be burned up, he shall suffer loss. But he shall be saved, yet so as by fire.
