For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts.
Isaiah 55:9
God uses the heavens being higher than the earth as an analogy to show that his ways and his thoughts (heavens) are higher than our ways and thoughts (earth). But in considering the full testimony of scripture, many of us may have missed that the coming of Christ changed this dynamic.
Scripture refers to us as earthy or heavenly:
As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly.
1 Corinthians 15:48
Heavenly or earthy are both used in reference to our behavior and the type of mind which guides it i.e. if our thoughts are heavenly, so also will be our ways, but if our thoughts are earthy, again, so also will be our ways.
1 Corinthians 15:47 The first man is of the earth, earthy: the second man is the Lord from heaven.
Until we are “born again“, we are functioning as “the first man” i.e. earthy or natural man. The thoughts and ways of the heavenly mind are seen as foolishness to the earthy or natural man:
1 Corinthians 2:14 But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.

But those born of the Spirit, have an heavenly orientation, the heavenly mind:
1 Corinthians 2:16 For who hath known the mind of the Lord, that he may instruct him? But we have the mind of Christ.
In Jesus, we see how God thinks and behaves i.e. his thoughts and ways. And with his mind in us, our thoughts and our ways are transformed so as to conform us to him (Rom 12:2)
Therefore, his ways and thoughts are higher than those who are earthy (carnally minded), but not of those who are heavenly i.e. Those who have his Spirit/mind in them.
1 John 4:17 …. because as he is, so are we in this world.