And we, who with unveiled faces all reflect the Lord's glory, are being transformed into his likeness with ever-increasing glory, which is from the Lord, who is the Spirit.
The context of this sentence is important. This comes at the end of a section about veils and glory. Paul is talking about how there was glory in the law, when God gave it to Moses, but how the glory that comes with the gospel of Christ is greater.
He says Moses would wear a veil because his face would shine, because he had been with God, and that is why he talks about how we, who have been saved by Christ, have faces that shine without veils. The glory from Christ is the fulfillment and the fuller glory.
First, it is profound that we reflect the Lord's glory, because it means we have been with him, or rather that he has been with us. This reminds us also where glory comes from: the Lord. Wouldn't that be a good thing to remember? How much time and anxiety could we save if we could just remember that?
God is still with us, and this has an effect on us. It transforms us into his likeness. The Christian life can feel like it has many complex and varied parts that you have to get right, but really there is one thing, and that is to be with God.
To be with him is to become more like him. To be with him is to know him more, to love him more, to respect him more, to desire him more, to obey him more. Another way of putting this is "remaining in Christ."
I am the vine; you are the branches. If a man remains in me, and I in him, he will bear much fruit; apart from me you can do nothing.