This may not make sense on first blush, but it's not hard to understand: Because we are born again, we have received God's salvation, but we are also waiting for God's salvation, which is ready to be revealed in the last time, as Peter says in 1 Peter 1:5. Let me clarify:
The "now-and-not-yet" concept is central in God's infallible, inerrant Word. What we're talking about here, salvation, is much on the same plane as God's Kingdom, and even Jesus's coming (first coming, 2000 years ago) and return (second coming, at some point in the future). In a very real sense, God's Kingdom is here now (and has been for 2000-plus years). It came with Jesus; He brought it. But, too, it is not yet here in its fullness; that will not be the case until Jesus returns. This is what we call the "now-and-not-yet" of the Gospel.
Very similarly, we have been saved (justified by God and imputed with the righteousness of Christ, born again of the Spirit). But, too, we are being saved and will not be fully redeemed until Jesus returns; God will bring to completion the good work He began in us at the day of Christ (Philippians 1:6). Again, the "now-and-not-yet" of the Gospel. But, of course, even though "not yet," all this is an absolute certainty. Jesus made it so with His work on the cross; this is precisely what He was saying in crying out, "It is finished!" So we can live now as if it's already done. All God's promises have their 'yes' and 'amen' in Christ Jesus.
Grace and peace to all.