This is how John appeared as a witness. When the Jews sent priests and Levites from Jerusalem to ask him, ‘Who are you?’ he not only declared, but he declared quite openly, ‘I am not the Christ.’ ‘Well then,’ they asked ‘are you Elijah?’ ‘I am not’ he said. ‘Are you the Prophet?’ He answered, ‘No.’ So they said to him, ‘Who are you? We must take back an answer to those who sent us. What have you to say about yourself?’ So John said, ‘I am, as Isaiah prophesied:
a voice that cries in the wilderness:
Make a straight way for the Lord.’
Now these men had been sent by the Pharisees, and they put this further question to him, ‘Why are you baptising if you are not the Christ, and not Elijah, and not the prophet?’ John replied, ‘I baptise with water; but there stands among you – unknown to you – the one who is coming after me; and I am not fit to undo his sandal-strap.’ This happened at Bethany, on the far side of the Jordan, where John was baptising.
Source: Jerusalem Bible
Catechism of the Catholic Church
THE SPIRIT OF CHRIST IN THE FULLNESS OF TIME
John, precursor, prophet, and baptist
717 “There was a man sent from God, whose name was John.” John was “filled with the Holy Spirit even from his mother’s womb”90 by Christ himself, whom the Virgin Mary had just conceived by the Holy Spirit. Mary’s visitation to Elizabeth thus became a visit from God to his people.
718 John is “Elijah [who] must come.” The fire of the Spirit dwells in him and makes him the forerunner of the coming Lord. In John, the precursor, the Holy Spirit completes the work of “[making] ready a people prepared for the Lord.”
719 John the Baptist is “more than a prophet.” In him, the Holy Spirit concludes his speaking through the prophets. John completes the cycle of prophets begun by Elijah. He proclaims the imminence of the consolation of Israel; he is the “voice” of the Consoler who is coming. As the Spirit of truth will also do, John “came to bear witness to the light.” In John’s sight, the Spirit thus brings to completion the careful search of the prophets and fulfills the longing of the angels. “He on whom you see the Spirit descend and remain, this is he who baptizes with the Holy Spirit. And I have seen and have borne witness that this is the Son of God. . . . Behold, the Lamb of God.”
720 Finally, with John the Baptist, the Holy Spirit begins the restoration to man of “the divine likeness,” prefiguring what he would achieve with and in Christ. John’s baptism was for repentance; baptism in water and the Spirit will be a new birth.
The LORD is king; let the earth rejoice; let the many islands be glad.
Cloud and darkness surround the Lord; justice and right are the foundation of his throne.
Fire goes before him; everywhere it consumes the foes.
Lightning illumines the world; the earth sees and trembles.
The mountains melt like wax before the LORD, before the Lord of all the earth.
The heavens proclaim God’s justice; all peoples see his glory.
All who serve idols are put to shame, who glory in worthless things; all gods bow down before you.
Zion hears and is glad, and the cities of Judah rejoice because of your judgments, O LORD.
You, LORD, are the Most High over all the earth, exalted far above all gods.
The LORD loves those who hate evil, protects the lives of the faithful, rescues them from the hand of the wicked.
Light dawns for the just; gladness, for the honest of heart.
Rejoice in the LORD, you just, and praise his holy name.
Source: The New American Bible
Basil of Caesarea, also called Saint Basil the Great (Greek: Ἅγιος Βασίλειος ὁ Μέγας, Ágios Basíleios o Mégas, Coptic: Ⲡⲓⲁⲅⲓⲟⲥ Ⲃⲁⲥⲓⲗⲓⲟⲥ; 329 or 330 – January 1 or 2, 379), was the Greek bishop of Caesarea Mazaca in Cappadocia, Asia Minor (modern-day Turkey). He was an influential theologian who supported the Nicene Creed and opposed the heresies of the early Christian church, fighting against both Arianism and the followers of Apollinaris of Laodicea. His ability to balance his theological convictions with his political connections made Basil a powerful advocate for the Nicene position.
In addition to his work as a theologian, Basil was known for his care of the poor and underprivileged. Basil established guidelines for monastic life which focus on community life, liturgical prayer, and manual labour. Together with Pachomius, he is remembered as a father of communal monasticism in Eastern Christianity. He is considered a saint by the traditions of both Eastern and Western Christianity.
Basil, Gregory of Nazianzus, and Gregory of Nyssa are collectively referred to as the Cappadocian Fathers. The Eastern Orthodox Church and Eastern Catholic Churches have given him, together with Gregory of Nazianzus and John Chrysostom, the title of Great Hierarch. He is recognised as a Doctor of the Church in the Roman Catholic Church. He is sometimes referred to by the epithet Ouranophantor (Greek: Οὐρανοφάντωρ), “revealer of heavenly mysteries”.
Gregory of Nazianzus (Greek: Γρηγόριος ὁ Ναζιανζηνός Grēgorios ho Nazianzēnos; c. 329 – 25 January 390), also known as Gregory the Theologian or Gregory Nazianzen, was a 4th-century Archbishop of Constantinople, and theologian. He is widely considered the most accomplished rhetorical stylist of the patristic age. As a classically trained orator and philosopher he infused Hellenism into the early church, establishing the paradigm of Byzantine theologians and church officials.
Gregory made a significant impact on the shape of Trinitarian theology among both Greek- and Latin-speaking theologians, and he is remembered as the “Trinitarian Theologian”. Much of his theological work continues to influence modern theologians, especially in regard to the relationship among the three Persons of the Trinity. Along with the brothers Basil the Great and Gregory of Nyssa, he is known as one of the Cappadocian Fathers.
Gregory is a saint in both Eastern and Western Christianity. In the Roman Catholic Church he is numbered among the Doctors of the Church; in the Eastern Orthodox Church and the Eastern Catholic Churches he is revered as one of the Three Holy Hierarchs, along with Basil the Great and John Chrysostom.
He is also one of only three men in the life of the Orthodox Church who have been officially designated “Theologian” by epithet, the other two being St. John the Theologian (the Evangelist), and St. Symeon the New Theologian.