Jesus tells Philip, after He institutes the Last Supper, that he who sees Jesus sees the Father. He then speaks of the coming Ascension, "Because I go to the Father." (John 14)
The commemoration on May 2 is that of St. Athanasius, Bishop, Confessor, Doctor. Against Arius, Athanasius defended the divinity of Jesus in the 4th century. "We preach not ourselves, but Jesus Christ our Lord; and ourselves your servants through Jesus." (2 Cor. 4:5-14)
The medieval church took Paul's reference in Ephesians 2 about the church being "built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone" as a basis for equating the honor of apostles' days with that of Sundays.