This verse really hit me this morning...
Hear my prayer, LORD, listen to my cry for help;
do not be deaf to my weeping.
I dwell with you as a foreigner,
a stranger, as all my ancestors were.
Psalm 39:12, TNIV
This is a "Psalm of David", which roughly means it was written by / with / for / in memory of David. And yet the author says that they only ever dwelt with God as a stranger and a foreigner. He sees a qualitative gap between him and God.
And yet, while even David saw that, we can now dwell with God as sons, rather than as strangers and foreigners.