Former Condition (21): Paul now applies the truth of reconciliation (1:20) to his direct audience. He first reminds them of their "former" condition of being excluded and hostile. Exclusion is the inability to engage with someone. Like being locked out of a room, so we were separated from God. But we weren't like loved ones separated against their will. We alienated ourselves by our own choice. We showed hostility toward God, actively, with our minds and with our evil deeds. It was our sins that separated us from God (Isaiah 59:2).
Reconciliation (22): But the Father reconciled us through the body of His incarnate Son, specifically, His death on the cross (1:20). And He did this to present us before Christ as a people "holy and blameless and beyond reproach," even those made "complete in Christ" (1:28). He reconciled us through Christ and sanctifies us in Christ to offer us to Christ (1:13-14)!
Steadfastness (23): All who stay in the faith (as revealed in Scripture) are truly in this relationship with God. The saved are like a building with firm foundations. They are "steadfast." They are not continually distracted from their hope (1:5, 27) as promised in the gospel. They have staying power.
 Paul last spoke of his audience in 1:14 ("we have redemption"). His focus thenceforth has been on Christ.
 The verb ap-a-llo-tri-o-ō (ἀπαλλοτριόω) means exclusion. Paul uses the word this way in Eph. 2:12 and 4:18.
 Since we are reconciled to God (1:20), it is only natural that in exclusion, we are separated from Him.
 Paul literally says, "in the body of His flesh." This means Christ physically died for our sins (1 Cor. 15:3-4).
 The presenting of the redeemed to Christ is repeated in the NT (2 Cor. 11:2; Eph. 5:27). This best fits here.
 The verb e-pi-me-nō (ἐπιμένω) means to remain/stay, even used of a traveler’s stay (1 Cor. 16:8; Gal. 1:18).
 The gospel Paul (and the other apostles) proclaimed (1:23b) is given to us in Scripture.
 "Firmly established" is a perfect participle that depicts the metaphor of laying down a building foundation.
 Scripture repeatedly speaks thus of believers. Cf. Rom. 8:18-25; 1 Thess. 1:9-10; Tit. 2:11-14; Heb. 3:5-6.