In Christian usage the term Trinity expresses the belief that there is only "one God" (Deuteronomy 6:4; 1 Timothy 2:5) who exists as three distinct divine persons, Father, Son, and Holy Spirit (Matthew 28:19), who are cosubstantial, coeternal, and coequal. While each divine person has particular roles and functions (e.g., Ephesians 1:3-14), all three work together in perfect accord (John 5:17, 19; 10:28-30). The doctrine of the Trinity is to be distinguished (1) from tritheism, which teaches the existence of three gods rather than only one God (cf. Deuteronomy 6:4), and (2) from modalism, which denies the coexistence of the three divine persons by teaching that God exists and manifests Himself as only one divine person at once (cf. Matthew 3:16-17).

This topic is from the Lockman Foundation.