Reconcilation is a change from enmity to friendship. It is mutual, i.e., it is a change wrought in both parties who have been at enmity.
(1.) In Col 1:21,22, the word there used refers to a change wrought in the personal character of the sinner who ceases to be an enemy to God by wicked works, and yields up to him his full confidence and love. In 2Co 5:20 the apostle beseeches the Corinthians to be "reconciled to God", i.e., to lay aside their enmity.
(2.) Ro 5:10 refers not to any change in our disposition toward God, but to God himself, as the party reconciled. Romans 5:11 teaches the same truth. From God we have received "the reconciliation" (R.V.), i.e., he has conferred on us the token of his friendship. So also 2Co 5:18,19 speaks of a reconciliation originating with God, and consisting in the removal of his merited wrath. In Eph 2:16 it is clear that the apostle does not refer to the winning back of the sinner in love and loyalty to God, but to the restoration of God's forfeited favour. This is effected by his justice being satisfied, so that he can, in consistency with his own nature, be favourable toward sinners. Justice demands the punishment of sinners. The death of Christ satisfies justice, and so reconciles God to us. This reconciliation makes God our friend, and enables him to pardon and save us. (See Atonement.)
Source: Easton's Bible Dictionary
More from Jim Hill:
Reconciliation is a relational concept in contrast to the judicial concept of justification, and is a restoration of fellowship with God who no longer holds our sins against us. We need to be reconciled because we were formerly far off from God (Eph 2:12), and it was only through His grace in sending Jesus to die for our sins that we can be brought back into fellowship. Our faith does not reconcile us to God, but the object of our faith, Jesus Christ, does. Believers can be assured that they have passed from condemnation to eternal life if they trust in the finished work of Jesus Christ (1 John 5:13 c.f. Eph 2:8-9).