Mert Goddesses
The two Mert goddesses, the twin sisters Isis and Nephthys, "providing Osiris with air", as Wallis Budge (1911) puts it, depicted on the walls of the Dendera Temple (30AD), in the one of the storyboard scenes of the Death and Resurrection of Osiris. [2]
In religio-mythology, Mert goddesses, “Meri sisters”, "Mertae-sisters" (Massey, 1907), or “sister-Mert goddesses” (Ѻ), from the root Mere meaning “sea” (Ѻ), refers to the twin Egyptian goddesses Isis, aka Sirius, or “star of the sea”, i.e. Stella Maris, as the Greeks and Romans referred to her (Jordan, 2001), in astro-theological terms, and Nephthys, her sister; these, in the Roman recension (see: recension theory), became the Mary pairs, figures, or characters seen profusely in the Bible.

Overview
The general overview of the two Mert goddesses is as follows: [1]

Isis and Nephthys prepared the funeral bed for their brother Osiris, and together they made the swathings wherewith his body was swathed after death; they assisted at the rising of the sun god when he rose upon this earth for the first time, they assisted at the resurrection of Osiris, and similarly, in all ages, they together aided the deceased to rise to the new life by means of the words which they chanted over his bier.”

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Osiris | Death and Resurrection
In the famous astro-theological based myth of the death and resurrection of Osiris (aka Passion of Osiris), Isis and Nephthys are the two female goddesses that first collect all the 14 pieces (phallus aside) of the dismembered Osiris, making him into a mummy, and then perform the magical acts of the awakening ceremony to bring him back to life:
Resurrection of Osiris
The four awakening scenes shown above are from the Dendera Temple.

Jesus reborn 4
Mary and Mary Magdalene at the tomb of Jesus the day he was resurrected from the dead, which is a monotheistic rewrite of the role the two Mert goddesses, Isis and Nephthys, played in the resurrection of Osiris.
Bible
In the Bible, the magical resurrection powers of the two Mert goddesses, were rewritten, in coded format, via the literary use of pairs of Mary figures used predominately throughout the various stories of Christianity, e.g. how Mary and Martha were present during the Raising of Lazarus, or how Mary and Mary Magdalene had to climb "on top of" the sepulcher of Jesus before he could be resurrected.

“And when Joseph [god Geb] had taken the body, he wrapped it in a clean linen cloth, And laid it in his own new tomb, which he had hewn out in the rock: and he rolled a great stone to the door of the sepulchre, and departed. And there was Mary Magdalene, and the other Mary, sitting over against the sepulcher.”
— Anon (300AD), Bible (Matthew 27:59-61)

Two "Mary" had to sit "over and against" the sepulcher of Jesus before he could be reborn, after being dead for three days, just as the two Mert goddesses did before Osiris could be reborn.

In 1907, Gerald Massey, referring to the two Biblical Marys as "Mertae-sisters", explained this Egyptian to Christian jump as follows: [4]

“The two Mertae-sisters are the watchers over the dead Osiris. They are also the mourners who weep over him when he is anointed and prepared for his burial. It is said of Osiris that he was triumphant over his adversaries on the night when Isis lay watching in tears over her brother Osiris (ch. 18). But the Mertae-sisters both watch and both weep over the dead body. In the vignettes to the ritual one of the two stands at the head and one at the feet of the body on the bier.

Anointing of Jesus
The anointing of the feet and head of Jesus by the two Meri sisters, which are monotheistic rewrites of the anointing of Osiris by the Mert goddesses. [5]
These two mourners, weepers, anointers, or embalmers, appear in the Gospels as two different women. According to John, it was Mary the sister of Martha who anointed Jesus for his burial. And as these are the two divine sisters in historic guise we ought to find one at the head of the victim and one at the feet, as, in fact, we do so find them. In the account furnished by Luke it is said that the woman who stood behind at the feet of Jesus weeping "began to wet his feet with her tears, and wiped them with the hair of her head" (Luke vii. 38). No name is given for the woman who was "a sinner," which seems to denote the other Mary called Magdalene. Matthew also omits the name of the woman with an alabaster cruse or flask. In keeping with the mythos this other one of the two Mertae-sisters should be Martha, but the point is that the woman with the cruse does not anoint the feet of Jesus. She poured the ointment "upon his head as he sat at meat" (Matt. xxvi. 7). Thus we see there are two different women who anoint Jesus, one at the head, one at the feet, even as the two divine sisters of Osiris called the Mertae, or watchers, stand at the head and feet of Osiris, when preparing him for his burial, or watching in tears, like Isis, the prototype of the woman who never ceased to kiss the feet of Jesus since the time when he had come into the house (Luke vii. 45-6). We have identified the other sister Nephthys, the mistress of the house, with the housekeeper Martha, and as Nephthys also carries the bowl or vase upon her head, this may account for the vessel of alabaster that was carried by the "woman" who poured the ointment on the head of Jesus, whereas Mary the sister of Martha poured it on his feet. Martha is one of the two Mertae by name. In the Egyptian mythos the two Mertae are Isis, the dear lover of Horus the Lord, bowed at his feet, and Nephthys mourning at his head (Naville, Totdenbuch, V. I., Kap. 17, A. g. and B. b.).”

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Sirius A and Sirius B (Isis and Nephthys)
In 1976, Robert Temple speculated that Isis and Nephthys, aka the Mert goddesses that raised the Orion constellation, were representative of the twin stars Sirius A and Sirius B. While Isis, astro-theology, has been verified to have been associated with Sirius (aka Sirius A), the second smaller star Sirius B was not discovered until 1862. The star Nephthys is associated with is unknown.
Sirius B
In 1976, Robert Temple, to note, in his the Sirius Mystery, asserted the interesting but untenable view that the Dogon people, of Mali, West Africa, knew that Sirius was a binary star (Sirius A and Sirius B). Here, if Temple's hypothesis were true, we would note that Osiris (aka Orion) has to be "raised" in the presence of not only Sirius (or Sirius A), aka Isis (or Stella Maris), but also by its twin star Sirius B, aka Nephthys (Maris’ sister). [3] Sirius B, however, is invisible to the naked eye. It was first predicted on dynamical grounds in 1844 and first observed in 1862. (Ѻ) The first telescope, moreover, was not invented until 1608 (by Hans Lippershey). (Ѻ) The so-called Temple hypothesis, namely that Egyptians knew about Sirius B, accordingly, while curious, seems doubtful.

Quotes
The following are representative quotes:

Nephthys also, like Isis, has many forms, for she is one of the two Maat goddesses [see: Maat], and she is one of the two Mert goddesses, and she is one of the two plumes which ornamented the head of her father Ra.”
Wallis Budge (1904), The Gods of the Egyptians, Volume Two [1]

“According to the interpretation of the art critics, the ship floating on its timeless sea is the barque of Isis, the paramount goddess of Egypt, whom the Greeks and Romans called Stella Maris, Star of the Sea. The primeval water of life surges from a fount of belief that was venerable long before Mary and Joseph waked the earth.”
Michael Jordan (2001), The Historical Mary (xiv)

“Oh, more than that, even thousands of years earlier. Yeah, this was my astonishment. When I read for the first time, a story that I had known – I used to be a professor of the New Testament – a story that had always been problematic for me, the ‘Raising of Lazarus’, which is in the fourth gospel, and is the most dramatic miracle, that Jesus is supposed to have carried out. He raised a man from the dead, that was supposed to have been dead for four days. He was really dead. When I came across that story, in all its full detail, in an Egyptian dress, in an Egyptian setting, right down to the two marries (Martha and Mary), and to the coming forth out of the tomb, in every detail, in 1700 before the common era, 17 centuries earlier, I realized I was on to something.”
Tom Harpur (2004), interview with Allan Gregg, on his The Pagan Christ

“As with Orpheus and Eurydice, the constellation of Isis and Osiris can also be compared with Mary and Jesus. The scene of the Pieta, in which Mary holds the corpse of the crucified Jesus on her lap and mourns, is comparable depiction of the body-centered intensity of female grief, in which Mary is assisted by Mary Magdalene, just as Isis is assisted by Nephthys.”
— Jan Assmann (2015), Death and Salvation in Ancient Egypt (pg. 116)

References
1. Budge, Wallis. (1904). The Gods of the Egyptians, Volume Two (pg. 256; overview, pg. 259). Dover, 1969.
2. (a) Mariette, Auguste. (1873). Dendera (Denderah), Volume Four (pg. 75). Paris: Publisher.
(b) Budge, Wallis. (1911). Osiris and the Egyptian Resurrection, Volume Two (pg. 51). P.L. Warner.
3. Scranton, Laird. (2006). The Science of the Dogon: Decoding the African Mystery Tradition (pg. 128). Inner Traditions.
4. Massey, Gerald. (1907). Ancient Egypt, the Light of the World: A Work of Reclamation and Restitution in Twelve Books, Volume 2 (Osiris, anointed, oil, pgs. 878-81). T.F. Unwin.
5. Thims, Libb. (2016). Smart Atheism: For Kids (pdf | 309-pgs) (anointing of Jesus, pg. #). Publisher.

Videos
● Anon. (2011). “Super True Stories: Mary, Mary, Mary, Mary, Mary and Mary” (Ѻ), LutheranSatire, Episode 2.5, May 15.

External links
Meret – Wikipedia.
Meret – GodChecker.com.

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