Catechism Part 1, Section 2, Chapter 2, Article 7: From thence he will come again to judge the living and the dead (668-682)

I- He will come again in glory (668-677)
After his ascension, Jesus possesses all power in heaven and on earth. He is also the head of the Church and reigns through the church. However, his reign has yet to be fulfilled and is under attack by evil until Christ comes again. This is a time of waiting and watching for Christ's return. The second coming of Christ could come at any moment, but it is suspended until his recognition by "all Israel."This is why Christians pray above all in the Eucharist, to hasten Christ's return by saying to him Our Lord, come! Before Christ comes again, the Church will undergo a period of trial by the deception of the Antichrist one who will come and claim to be God but is not. Because of this, the Church rejects all claims to a messianic kingdom before the eschatological second coming. Only through this trial will the Church be able to follow Christ into heaven.

II- To judge the living and the dead (678-679)
When Jesus comes again, all secrets of the heart and conduct will be judged, and the unbelief that rejects grace will be condemned.  Our attitude about our neighbor will disclose acceptance or refusal of grace and divine love. Christ is Lord of eternal life. Full right to pass difinative judegment on the works and hearts of men belongs to him as redeemer of the world. Christ did not come to condemn the world; as one condemns oneself by rejecting God's grace and the Spirit of love.