A disciple of John the Baptist, Andrew heard him refer to Jesus as the Lamb of God. Andrew asked for an audience and saw Jesus for a day, then proclaimed, "We have found the Messiah," in itself a creed and confession for the Christian faith.

He brought his brother, Simon-Peter, to Christ. Although not one of the inner circle, he played the first role in several events which are recorded. Eusebius in his Church History states that Andrew later went to Scythia. According to tradition he was martyred at Patras, Greece, crucified on an X-shaped cross, which since has become known as St. Andrew's Cross. He is regarded as being connected with the writing of St. John's Gospel. According to tradition, he is the founder of the Ecumenical Patriarchate of Constantinople.