Cleaving to the Lord

Whose authority are we under as Christians? Peter defended his ministry to the Gentiles asking a rhetorical question to the accusation made, "Who am I to withstand God?". The Gospel spread rapidly, as the hand of the Lord was with them, and others were called to assist. Barnabas exhorted them to "Cleave to the Lord with purpose of heart". We should do the same remembering we are under Christ and His authority.