Can anyone share with me just where the idea that the FULL MOON has to be on the 15th of the month.
Are there Scriptures that say this, or at least allude to it, or perhaps somewhere within the writings of Philo or Josephus?
There is no where in scripture to back up that the full moon is on the 15th.
There is much more evidence that a full moon, the lesser light that rules the night (Gen 1:14) is the New Moon.
This below is central to why Yahweh ordained the full moon, when we come before him on the appointed times, to, as it were, to congregate (H4150), stand before him;
The Day of the first new moon, day 5 on the first cycle of weeks, (day five not Day one in the first week) the temple gates are opened, at erev, (evening to evening). Eze 4 :1 ‘Thus said the Master yahweh, “The gate of the inner courtyard facing east is shut the six days of work, but on the Sabbath it is opened, and on the day of the New Moon(th) it is opened.
This must be a full moon as it rises in the east after sunset.
It cannot be the crescent new moon, as this lesser (inferior) light sets within three hours in the west after sunset, against the west gate.
Eze 4 :3 “And the people of the land shall also bow themselves at the entrance to this gate before Yahweh, on the Sabbaths and on the (full) New Moons.
The full moon rising in the east will be to our backs. The sun has already set, gone down.
Psa 104:19 He made the moon for appointed times; The sun knows its going down.
The so called new and inferior crescent moon, is visible at late evening, setting in the west, will be just up above our line of sight.
Deu 4:19 and lest you lift up your eyes to the heavens, and shall see the sun, and the moon, and the stars – all the host of the heavens – and you be drawn away into bowing down to them and serving them, which יהוה your Elohim has allotted to all the peoples under all the heavens.
They must be standing at the west gate to have there backs turned to the sun and crescent moon. Standing at the west gate gate (as it were) is deemed as Sun worship. Notice all Christos cemeteries the bodies are buried towards the east, Headstones facing the rising sun.
When the New temple is established at His return, in the 8th millennium, we learn;Rev 21:13 three gates on the east, three gates on the north, three gates on the south, and three gates on the west.
Unfortunately not many are prepared to challenge let alone take an objective look at the status quo, and search out this matter.
If you keep the astronomical New Moon, the Full Moon will be on the 15th. So Matsa and Sukkot will begin on a Full Moon. If you go by the first crescent, the Full Moon is irrelevant.
Psalm 81:3 is evidence that the New Moon is dark. Also I posted a page on the subject of why the New Moon is the astronomical conjunction.