In Matthew 7, we have Jesus saying to his disciples: "Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but only the one who does the will of my Father in heaven. Many will say to me on that day, 'Lord, Lord, did we not prophesy in your name? Did we not drive out demons in your name? Did we not do mighty deeds in your name?' Then I will declare to them solemnly, 'I never knew you. Depart from me, you evildoers.'" It is obvious that we should not ever try to justify ourselves before God, for doing so amounts to letting him know that he doesn't know everything about us! Begging for mercy is OK, but not telling him how to judge. The time to prepare for entering the kingdom of heaven is now so that we may anticipate the arrival of that day with joy.