21 “And although you were previously alienated and hostile in attitude, engaged in evil deeds, 22 yet He has now reconciled you in His body of flesh through death, in order to present you before Him holy and blameless and beyond reproach— 23 if indeed you continue in the faith firmly established and steadfast, and not shifting from the hope of the gospel that you have heard, which was proclaimed in all creation under heaven, and of which I, Paul, was made a minister.”
Paul is speaking of the nature problem found inherently in humanity. When we are born into this world, we are alienated from relationship with God and hostile towards Him because we are spiritually dead. But in Christ we are holy and blameless and beyond reproach. All who believe are found innocent and made righteous in Christ (2 Corinthians 5:21).
If indeed: Paul is speaking to a large group of people. Some had heard the Gospel and believed. But in such a large group, some may have only heard the Gospel and not made a response. Some may have even heard the Gospel and faced temptation to return to their previous pagan temple. Therefore, Paul is speaking of the importance of having an abiding faith, a real faith, in Jesus. When there is real faith, we are made completely holy and blameless and beyond reproach.