True, at some point judgement will come upon all of us. But up until that time, we can show mercy and repent of the hardness of hearts. The atonement of Christ is free for all to take advantage of and receive forgiveness of sin until the day of judgement. And during judgement, the Lord could show us all our past sins and but also know that we repented of them and forsook them and changed our ways. He can then say, "come ye blessed of the Lord and enter into my kingdom", for mercy does triumph over justice for those who do the works of repentance and righteousness even though in times past they fell short of the glory of God through sin. It isn't the atonement that is limited but it is the unrepentant soul who has the chance to repent but choose to remain in sin and not follow after the grace of Jesus Christ who are found guilty at the judgement. The atonement bring upon all mankind the resurrection and immortality but it cannot allow the wicked into God's kingdom unless they repent and forsake their sins and receive the forgiveness of Jesus Christ through his grace and mercy.James 2: 13 For judgment is without mercy to the one who has shown no mercy.
Mercy triumphs over judgment.
Hebrews 10: 28 Anyone who has rejected Moses’ law dies without mercy on the testimony of two or three witnesses.
Can Men that Rob God Read Malachi 3:7-18
A man who robs God of tithes but never repents of it is not willing to abide by the law of God's kingdom but he who realized that he has robbed God and repents and makes remuneration for his sin can find forgiveness up until the day of judgement. This is the same for those who break the law of Moses. Repentance and forgiveness are unto all mankind but the period of grace can come to an end at the day of judgement. We should therefore seek to repent and ask for forgiveness of God until we stand before Him in the great day of judgement.
Isaiah 1:16-18
16 Wash you, make you clean; put away the evil of your doings from before mine eyes; cease to do evil;
17 Learn to do well; seek judgment, relieve the oppressed, judge the fatherless, plead for the widow.
18 Come now, and let us reason together, saith the Lord: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool.
The whole purpose of the atonement was to allow God's children to repent and forsake their sins and find forgiveness as they progress to becoming better beings and to save them from Adam's transgression and make them immortal. The resurrection is a grace or gift to all mankind regardless of their lack of repentance. However, mankind must repent and forsake sin and be willing to live the law of the kingdom of heaven or they will not find entrance therein.