I think that when we are sinless we will still fear God in the sense of reverential, trembling awe — as when we stand on a peak before vast stretches of unscalable cliffs. And we will also fear, I suppose, in the sense of shuddering with thankfulness that we are not among the number who still dishonor God.
But the painful fear, the guilty fear, the craven fear, the humiliating fear — all such fear will one day be taken way. But only in the way God intends. And in his time. We should not be done with it in the wrong way, or too soon.
Here is the way C. S. Lewis puts it:
Perfect love, we know, casteth out fear [1 John 4:18]. But so do several other things — ignorance, alcohol, passion, presumption, and stupidity.
It is very desirable that we should all advance to that perfection of love in which we shall fear no longer; but it is very undesirable, until we have reached that stage, that we should allow any inferior agent to cast out our fear. (“The World’s Last Night” in C. S. Lewis: Essay Collection and Other Short Pieces, 51)