Paul, who saw as few have ever seen, said we now see through a glass darkly, or like a dim/rather distorted image in a mirror (1 Corinthians 13). We are limited. On occasion, though it seems rare, we sometimes catch a clear glimpse of truth, more like get immersed into something of the reality of truth. A couple of examples probably more or less common to us all in Jesus: a sense of our sin as offensive to God and a violation of love against both God and neighbor. And the righteousness, peace and joy that is simply a part of God’s love in his grace and kingdom in Jesus, which can flood our hearts by the Holy Spirit (Romans 5).
Much of the time, at least in my experience, and I think I’m not alone, we live in a faith which accepts truth revealed from God, at the heart of that, the truth of the gospel. But truths like God is our Father, we are his children, our relationship to God is through Jesus, etc., etc. We accept everything as we understand it, which we may often acknowledge, not very well. But in all our weakness and we can even say sin since we still do sin, we believe it in the midst of a denying world and even with all of our doubts.
I think over time, imperceptibly by us since it’s gradual and since we remain limited as creatures and still quite susceptible to sin, but over time what we know by faith becomes more and more the reality in our lives. So that we know that God in Jesus by the Spirit is indeed our salvation. That in all of our weakness and yes, sin, we are ever in need of God and God’s salvation in Jesus. So that our perspective is more and more changed from whatever we once thought the world and reality is to the reality that shows up the falsehood of everything else.
In time our knowledge becomes reality. Not that this isn’t true in some measure genuinely at the onset of our salvation, when this begins to dawn on us. It seems like God usually makes it especially clear then. We must go on through dry, dark and dangerous places. Holding on to the faith of the gospel, to the truth that is in Jesus. A vital part of the knowledge we have through faith becoming more and more a reality. Destined to become the reality of the world in and through Jesus.