Mary Poppins appears to people as a kindly nanny. Despite her appearance she can fly and alter reality. She is revealed to be a manifestation of God when she confronts the Antichrist to prevent the Apocalypse, saving all humankind.
In 2009, Mina Murray and Orlando come into conflict with a young boy, who appears to be based on Harry Potter, that turns out to be the Antichrist. A dark entity they've been trying to prevent for the past century. Orlando's sword, Excalibur, sends a beam of light into the sky. This is to signal Prospero to send help.
As the Antichrist begins to destroy everything, Allan Quatermain joins the fight. He shoots the Antichrist in the face but the Antichrist quickly regenerates. The Antichrist then takes out its penis and uses it to shoot a bolt of electricity at Quatermain which kills him. Orlando begins slicing the Antichrist with Excalibur which proves to be useless as it keeps regenerating. Just when all hope seems loss, Mina and Orlando see a figure in the sky. Prospero finally sent someone to help.
While not identified as Mary Poppins, we can assume this is who she is. Poppins claims to be on every page of the Bible hinting to the fact that she is also God. The Antichrist then shoots fire out of its mouth at Poppins who survives without a single scratch. She declares the Antichrist to be a dreadful little boy and alters reality, turning him into a chalk drawing on the pavement. Poppins then says, "splish splash" and a thunderstorm begins, washing away the chalk drawing of the Antichrist, defeating him.
Poppins then tells Mina and Orlando they did a good job, takes the severed head of Oliver Haddo, and then floats away in the sky to an unknown destination.
Connection to God
Mary Poppins appears to represent Shekhinah, Binah, or Sophia.
From readings of the Talmud, Shekhinah represents the feminine attributes of God. Shekhinah is sometimes represented as a goddess of wisdom. In this sense, Mary Poppins is the personification of Skekhinah.
Sophia is a neopagan goddess of wisdom, and like Shekhinah, she can be associated with the feminine attributes of God. Hagia Sophia represents an understanding of the Holy Spirit.
Mary Poppins is a personification of all these concepts, and as such, she represents the feminine side of God that cares for the welfare of mankind.
Mary Poppins reveals her godly status by informing the Antichrist that she is on "every page" of the Bible, whereas he is in "just the one book".
Mary Poppins was created by P. L. Travers in several novels between 1934 and 1980. She is perhaps more familiarly associated with the 1964 Walt Disney musical film adaptation Mary Poppins. She is never named as "Mary Poppins" because the character is not in the public domain.