The Hillel II calendar followed by Jews and Messianic Jews is no longer God's Calendar!
4th-Century Corruption
The current calendar of the Jews and Messianic Jews is not based on the Biblical Calendar of God, but on the calendar of Hillel II (Hebrew: הלל נשיאה, Hillel de Nasi), or simply Hillel. He was the son and successor of Judah III and was in power between 320 and 385 AD.
Israel Brought Under Rome
On the apparent orders of his friend and Emperor Julian the Apostate, Hillel fixed God's lunar calendar and converted it into a lunisolar calendar. Rome found God's Calendar extremely troublesome and difficult for trade.
Roman Emperor Julian the Apostate was so grateful to Hillel for his fixation and "conversion calendar" that he ordered the tax bills for Israel to be thrown into the flames. Julian also publicly honored Hillel and called him "his friend".
• The lunar calendar of God YHWH was converted into a partly lunar, partly solar calendar running in cycles of 19 years. The further into the cycle, the more the annual calendar deviates from God's Calendar, off by more than 1 month!
• The determination of the New Moon was delayed, causing his new moon days to often fall too late, making the months and festivals start late.
• The year assigned 1 Tishri as New Year instead of the biblical 1 Nisan.
• 1 Nisan is calculated backwards from 1 Tishri
• and many more adjustments and delay rules.
In this way, Hillel II destroyed God's Calendar and thus brought all Jews who adhere to his calendar under Rome and its Babylonian idolatry with the guise of the Bible and of God.
Formally & personally under Rome
Hillel II also placed himself personally under Rome by having himself "baptized" on his deathbed—actually sprinkled—which makes you a member of the Roman Catholic Church, or in other words, brings you under Rome! Epiphanius of Salamis was a witness to this; Joseph of Tiberias was a convert and disciple of Hillel II
Practical consequences
1. 1 Nissan often falls too late, and consequently Passover does too. Up to more than 1 month late, the further you get into the 19-year cycle.
2.1 Nissan is calculated back from 1 Tishri instead of 1 Tishri following from the 1 Nissan determination.
3. The other Feasts also shift as a result, e.g., Pentecost Sunday (Feast of Weeks).
4. Not all New Moons are celebrated monthly anymore.
5. New Moons are determined within the 3-day period of invisibility instead of from the first moment of 0% (astronomical) visibility, so the New Moon falls later and the annual calendar shifts.
6. New Moons become a secular holiday instead of God's Day. New Year's Day, for example.
7. The Feast of Unleavened Bread on Hillel II coincides with Roman Easter Sunday, whereas with God's Calendar this is not always the case either!
The Hillel II calendar appears very authentic due to the names and days used, but it is an infringement on God's Calendar. Violating God's Statutes!
Whoever ignores, violates, or mixes God's Statutes with worldly ways, God's Wrath awaits. God takes away Blessing and Peace, fertility, His Protection and spiritual and physical health.
Deception upon deception
Besides this misleading, modified calendar, traditional Jews and Messianic Jews also have in common that they deny Yeshua as the son, Lord and High Priest of the one true GOD YHWH, Mar 16:19, Heb 8:1. In doing so, they make Yeshua the same as YHWH, thereby denying Yeshua's death on the cross, but also the words and the saving faith according to Yeshua in John 17:3. No wonder, then, that they choose the earthly and idolatrous for the Jewish cult and continue in deception.
Jewish people generally know nothing of this corrupted, misleading calendar that has been spoon-fed to them from childhood. My hope is that, regarding faith and calendar, they will want to accept the true biblical truth and let go of the corrupted, idolatrous aspect for their salvation!
And to that end want to determine God's Calendar and Feasts themselves everywhere in the world!
Choose the real thing, choose God's Feasts on His Calendar! Be glad with God's Feasts instead because they instill Gods Plan!
Sources:
https://en.wikipedia.org/wiki/Hillel_II
(See also the many references to historical sources therein!)