The ICOC affirms classical Trinitarian doctrine: God is one Being existing eternally as Father, Son, and Holy Spirit — three distinct persons of the one divine essence. This is non-negotiable and shared with the broader Churches of Christ tradition from which the ICOC emerged.

Trinitarian theology shapes ICOC baptism, which is administered in the name of the Father, Son, and Holy Spirit per Matthew 28:19, and its understanding of salvation as the work of the Triune God in calling, redeeming, and indwelling the believer.