The notion of a strictly solar calendar for the biblical year, divorced from lunar observation, has been advanced in certain interpretive circles, yet it encounters significant difficulties when examined against the primary scriptural evidence and linguistic data.

First: Extra-Canonical Sources

Proponents frequently appeal to extra-canonical works such as 1 Enoch and the Book of Jubilees to support a fixed 364-day solar framework with unchanging weekday alignments for the festivals. These texts, while influential in certain Second Temple Jewish sects, lack canonical authority within the Hebrew Bible and were not endorsed by the prophetic tradition or the New Testament writers. Reliance upon them introduces an external interpretive grid that risks violating the biblical injunction against adding to or subtracting from the given revelation (Deut 4:2; 12:32; cf. Rev 22:18–19). The canonical Scriptures present the calendar as a harmony of solar, lunar, and agricultural indicators without recourse to such supplementary sources.

Second: Linguistic Evidence

The assertion that חֹדֶשׁ (ḥōdeš, "new moon/month") denotes merely a generic "new month" unconnected to lunar phases, and thus compatible with a solar reckoning, is contradicted by biblical usage. The term is repeatedly paired with explicit lunar terminology in contexts that underscore the moon's role. Psalm 81:3 (Heb. 81:4) juxtaposes חֹדֶשׁ with כֶּסֶה (keseh, "full moon"): "Blow the trumpet at the new moon, at the full moon, on our feast day." Ezekiel 46:1–3 links the "new moon" (ḥōdeš) with Sabbath observances in a cyclical pattern tied to visible renewal. Most tellingly, Psalm 104:19 states, "He made the moon (יָרֵחַ, yārēaḥ) for appointed times (מוֹעֲדִים, mō'ădim); the sun knows its going down," explicitly connecting the moon to the mo'adim, of which the new moon is the inaugural marker (cf. Num 28:11–15; Isa 66:23). These passages demonstrate that חֹדֶשׁ (ḥōdeš, "new moon/month") functions as the visible lunar renewal, not an abstract solar interval.

Third: Incompatibility with Gospel Account

The traditional weekly cycle they utilize places Passover on a Tuesday and First Fruits (the 16th) is never the first day of the week. While this could be rectified by shifting their continuous cycle, it would no longer align with modern Saturday. Since we have already demonstrated that a Tuesday Passover is incompatible with the gospel account, these calendars are beyond our ability to reconcile.

Fourth: Undocumented Week Insertion

The 364-day solar calendar documented in the Dead Sea Scrolls requires inserting an undocumented week every 7 years to maintain synchronization with both the solar year and the weekly cycle. While some may object that lunar calendars also require a 13th month (which Scripture never explicitly mentions), there is a critical distinction: the 13th month is a natural consequence of aligning lunar months (~354 days) with the solar year (~365.25 days) to keep feasts in their proper seasons—a necessary adjustment for agricultural alignment. In contrast, the undocumented week insertion in a 364-day solar calendar is required because the system itself is fundamentally broken: it doesn't match the actual solar year, and its weekly cycle drifts out of alignment. This demonstrates that the calendar is mathematically and theologically unsustainable, requiring additions that have no scriptural basis or natural justification.

Fifth: Consecutive 15th Sabbaths

The Exodus narrative demonstrates that the 15th of both the first and second month were Sabbaths (Exodus 12:15-16; 16:1, 22-30). This is mathematically impossible with any solar calendar that maintains a continuous 7-day weekly cycle and fixed month lengths. If the 15th of month one is a Sabbath, then 29-30 days later (the 15th of month two) would shift by 1-2 days in a continuous cycle, making it impossible for both to be Sabbaths. This scriptural evidence directly refutes solar calendars that claim a continuous weekly cycle, as they cannot accommodate consecutive 15ths both being Sabbaths.

Conclusion

What this demonstrates is that these extra-biblical books are incompatible with the evidence from the Bible and should be viewed skeptically.

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Here is the patience (steadfastness, enduring, perseverance) of the saints (holy ones, blameless): here are they that keep the commandments of 𐤉𐤄𐤅𐤄, and the faith in Yeshua. — Revelation 14:12