In Catholicism it’s what communion is all about. It’s to know Him; the “knowledge of God” is what Jesus came to reveal, the full knowledge of the true God so that we may be reconciled with Him as we come to believe in Him, and so place our trust/hope in Him, and, ultimately and most importantly, come to love Him. This is a personal and direct knowledge even if not perfectly complete in this life, not simply “head knowledge”:
“For now we see only a reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known.“ 1 Cor 13:12
“Now” In the above verse is this life, “then” is the next life. Our faith, itself, as a supernatural gift, is said to be a sort of dim foretaste of that future “vision” of God where we meet Him “face to face”. And that faith is meant to grow as we continue to walk with God and exercise that faith; it can be more or less deep and strong. Consider these other verses that teach about this knowledge which is the basis of faith, of our relationship with God IOW:
No longer will they teach their neighbor,
or say to one another, ‘Know the Lord,’
because they will all know me,
from the least of them to the greatest,”
declares the Lord.
“For I will forgive their wickedness
and will remember their sins no more.”
Jer 31:34, part of the New Covenant prophecy of Jer 31:32-34
Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent.
This knowledge desires and means communion with God. The Eucharist is our sacramental way of acknowledging and experiencing this gift of Himself while prayer is the regular means of communicating with Him in seeking and In talking as a friend. But all of this will continue to be a struggle in this life, but a good one where, hopefully, with the help of His grace we grow nearer and nearer to Him and nearer to alignment with His will.
But there are many distractions and obstacles and temptations away from this union which man was made for, not the least of which is our own pride which has more to do with fear of man than fear of God. We don’t necessarily even want to know God. By his sin of disobedience Adam preferred Himself to God as the catechism teaches, effectively dismissing God as his God. We’re here to come to learn how wrong Adam was, and how much we need God.
Anyway, the ultimate goal of our faith is to come to love Him with our whole heart, soul, mind and strength, to fulfill the Greatest Commandment. To truly know God is to love Him in this way and to love Him in this way is to achieve our full justice, righteous, perfection: to reach our purpose, our teleios. But it will always involve struggle, until we’re fully and freely “bound” to Him as the catechism also teaches.