And you, that were sometime alienated and enemies in [your] mind by wicked works, yet now hath he reconciled
Note 17 at Col 1:21: Notice that this alienation and enmity between us and God is in our minds. It is not God who rejected us. We rejected God by exalting our own wisdom above the wisdom of God. Therefore, since our minds led us away from God, the renewing of our minds must be part of the process of restoring us back to God (see note 15 at Ro 8:6 and notes 7-9 at Ro 12:2).
At salvation, it is our spirits that are born again (see note 9 at 2Co 5:17). Our minds are not instantly changed. In fact, we have to make our thinking change by believing the truths of God's Word. Since the alienation was in our minds, we will continue to experience alienation even after we are born again, until our thinking changes.
Note 18 at Col 1:21: This reconciliation was accomplished through the death of our Lord Jesus (Col 1:22). The awful price that was paid indicates the greatness of the debt. This harmony wasn't cheap and should not be taken lightly.