The answer is rather simple. In the Book of Genesis we find that although God was the Lord, Master, and Creator of all, He nonetheless allowed mankind to exist upon the same plane because, God walked and talked to them in the Garden. However, after man chose to sin, he “fell” (both literally and figuratively) out of favor with God. This is why we refer to that moment of eating the forbidden fruit as the great Fall; and like any fall, man dropped down in his relationship and stature with God. It certainly wasn’t due to God raising Himself above man; man just lowered himself through sin.
Notice how in Holy Scripture, from that time forward, man’s quest to reconcile and gain back what he lost becomes an almost up-hill climb; perhaps manifested best by Jacob’s vision of a ladder reaching into heaven (Gen. 28:10-17). When man wanted to address or pray to God, he instinctively looked upward – and in many cases climbed upwards (e.g. Abraham, Moses, Elijah, Habbakuk). When he wanted to make any offerings, he burned these gifts so that they would rise with the smoke and go up. When he talked about God’s realm, he again naturally pointed towards the heavens.
Therefore St. Paul’s words, “Set your minds on things that are above, not on things that are of the earth” (Colossians 3:2), become an admonition to set our minds on things that are above and is perfectly warranted and justified. So let’s keep climbing the ladder of perfection upwards until we can get back to where we belong!