Quartodecimanism

Quartodecimanism (Latin: quarto decima, literally "fourteenth") is the traditional designation for the supersessionist, antitypical Jewish Christian observation of the feasts of Passover and Unleavened Bread in the month Nisan according to the Pentateuch command. The Ante-Nicene Fathers of the second century by and large were Quartodecimans, resisting the rapid degeneration of the proto-papal power in Rome towards Sunday-venerating pagan syncretism.

Epistle of Polycrates to Pope Victor

The Ante-Nicene Father Polycrates of Ephesus was embroiled in a controversy with the Roman Pope Victor in the second century over the observation of Passover, which the church of Rome came to oppose, presumably some time following the death of Clement. Polycrates argued that the Asia Minor churches' observation of the feast days was in accordance to early Christian tradition taught by the Apostles Philip and John:

“	As for us, then, we scrupulously observe the exact day, neither adding nor taking away. For in Asia great luminaries have gone to their rest, who shall rise again in the day of the coming of the Lord, when He cometh with glory from heaven and shall raise again all the saints. I speak of Philip, one of the twelve apostles, who is laid to rest at Hierapolis; and his two daughters, who arrived at old age unmarried; his other daughter also, who passed her life under the influence of the Holy Spirit, and reposes at Ephesus; John, moreover, who reclined on the Lord's bosom, and who became a priest wearing the mitre, and a witness and a teacher-he rests at Ephesus. Then there is Polycarp, both bishop and martyr at Smyrna; and Thraseas from Eumenia, both bishop and martyr, who rests at Smyrna. Why should I speak of Sagaris, bishop and martyr, who rests at Laodicea? of the blessed Papirius, moreover? and of Melito the eunuch, who performed all his actions under the influence of the Holy Spirit, and lies at Sardis, awaiting the visitation from heaven, when he shall rise again from the dead? These all kept the passover on the fourteenth. day of the month, in accordance with the Gospel, without ever deviating from it, but keeping to the rule of faith. Moreover I also, Polycrates, who am the least of you all, in accordance with the tradition of my relatives, some of whom I have succeeded-seven of my relatives were bishops, and I am the eighth, and my relatives always observed the day when the people put away the leaven-I myself, brethren, I say, who am sixty-five years old in the Lord, and have fallen in with the brethren in all parts of the world, and have read through all Holy Scripture, am not frightened at the things which are said to terrify us. For those who are greater than I have said, "We ought to obey God rather than men." ... I might also have made mention of the bishops associated with me, whom it was your own desire to have called together by me, and I called them together: whose names, if I were to write them down, would amount to a great number. These bishops, on coming to see me, unworthy as I am, signified their united approval of the letter, knowing that I wore these grey hairs not in vain, but have always regulated my conduct in obedience to the Lord Jesus.	”
—Polycrates's letter to Victor (Roberts–Donaldson translation)

Misconceptions

The majority of modern Christians believe that the feast days—and the entirety of the Mosaic Law—were nailed to the cross. They argue that the "ordinances" in the Torah were authoritatively abrogated in accordance to Paul the Apostle's letters to the Ephesians and Colossians:

“	For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us; having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace; and that he might reconcile both unto God in one body by the cross, having slain the enmity thereby: and came and preached peace to you which were afar off, and to them that were nigh.	”
—Ephesians 2:14–17

“	And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses; blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross; and having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.	”
—Colossians 2:13–15

However, the Koine Greek word translated as "ordinance" in those passages is δόγμασιν (dogmasin, literally "dogma," "decree," or "ordinance"), used primarily in reference to man-made commandments. Jesus Christ declared—as recorded in the Synoptics—that "man shall not live by bread alone, but by every word (that proceeds out of the mouth of) God." Therefore, the "ordinances" Paul spoke of were not the ceremonial commands in the Torah, rather the proto-rabbinic Pharisaic Mishnah dictates over the religious jurisdiction of Jewry at the time.