Holy Thursday and Feast of the Holy Martyr Eupsychius of Caesarea
YOU MUST ALSO keep this truth firmly fixed in your minds, that the Holy Spirit is of the same dignity as the Father and the Son. Christ said to His disciples: Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit (Matt. 28.19).
Did you see the exactness with which Christ makes profession of this truth? Did you see how unambiguous His instruction is? Let no one hereafter disturb your mind by brining the searchings of his own reason into the Church’s dogmas as he tries to confuse beliefs that are correct and sound. Avoid the companionship of such people as you would avoid drugs which could destroy you. For these people are more dangerous than poisonous drugs. The drugs do harm only to the body; these people destroy the very salvation of the soul. That is why it is fitting from the very beginning to avoid such discussions with these people, especially until you will be able, with the passage of time, to curb their impudent tongues, after you have fortified yourself well with the weapons of the spirit, the testimony of Holy Writ.
Such is the strictness we wish you so show in regard to the dogmas of the Church, and we desire you to keep them fast fixed in your minds. It is also fitting that those who manifest such faith shine forth by their conduct. Hence, I must also instruct in this matter those who are about to deserve the royal gift, so that you may be able to know that there is no sin so great that it can conquer the munificence of the Master. Even if one is a fornicator, or an adulterer, or effeminate, or unnatural in his lust, or has others, or is a drunkard, or an idolater, the power of the gift and the love of the Master are great enough to make all these sins disappear and to make the sinner shine more brightly than the rays of the sun, if he will only give evidence of good resolution.
—St John Chrysostom, Baptismal Instructions