"24 Now I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in Christ's afflictions for the sake of his body, that is, the church, 25 of which I became a minister according to the stewardship from God that was given to me for you, to make the word of God fully known, 26 the mystery hidden for ages and generations but now revealed to his saints. 27 To them God chose to make known how great among the Gentiles are the riches of the glory of this mystery, which is Christ in you, the hope of glory. 28 Him we proclaim, warning everyone and teaching everyone with all wisdom, that we may present everyone mature in Christ. 29 For this I toil, struggling with all his energy that he powerfully works within me.
2 For I want you to know how great a struggle I have for you and for those at Laodicea and for all who have not seen me face to face, 2 that their hearts may be encouraged, being knit together in love, to reach all the riches of full assurance of understanding and the knowledge of God's mystery, which is Christ, 3 in whom are hidden all the treasures of wisdom and knowledge. 4 I say this in order that no one may delude you with plausible arguments. 5 For though I am absent in body, yet I am with you in spirit, rejoicing to see your good order and the firmness of your faith in Christ."
Colossians 1:24 - 2:5
You will notice that Paul's labour and struggle in preaching the 'mystery of Christ' was to one specific end (v 28) '... so that we may present everyone perfect in Christ': It would seem that Paul has the Parousia in mind here. His intention is to present everyone perfect in Christ at that last day. And yet, even now, as we groan and struggle, longing for the final redemption of our bodies, Paul will not allow for anything less than full maturity for every believer. He will not allow us to remain as mere worldly infants in Christ. He expects us to be mature, grown-up Christians, with hearts wholly turned to God, as holy as it is possible for fallen man to be. While that perfection will only be finally and fully realised at the last trumpet, Paul is convinced that preaching the mystery of Christ contributes to the sanctifying and maturing process, as the word of God does/is allowed to do its deep work within us (Ephesians 6:26-27).