A Pillar of Fire was one of the manifestations of the presence of the God of Israel in the Torah, the five books of Moses which appear at the beginning of the Old Testament Bible. According to Exodus, the pillar of fire provided light so that the Israelites could travel by night during the Exodus from Egypt (claimed to be the 18th Dynasty; see dating of the Exodus). The pillar of fire is traditionally paired with the manifestation of the divine presence by day as the Pillar of Cloud. This was so they "could travel by day or night". YHWH, the God of Bible, manifested himself in this pillar of fire or cloud in order to directly guide and comfort the Israelites while he rescued them from their Egyptian slavery. Throughout the Israelite's time in the desert, traveling from Egypt to Canaan (The Promised Land), YHWH continually used this pillar of fire and cloud to lead his people and remind them of his presence. When the pillar of God moved forward, the people of Israel would pack up their camp and follow behind it. Similarly, when the pillar of God's presence stopped, the Israelites would set up camp underneath it. The Tabernacle of the Lord would be set up directly underneath the cloud of the Lord. This way, God's presence was visibly in the center of the camp at all times. YHWH's holy and awesome manifestation in the cloud among the people would inspire a righteous fear as well as a blessed assurance of their safety and favor.
The visible light of God's presence with his people in the Old Testament prefigures his visible return and presence in the "new heaven and new earth" brought about at the end of time. The apostle John of the New Testament prophecies in the book of Revelation about a day when God will return to earth and "make all things new". A part of this new creative order, according to Revelation 21, is that there will be "no need of sun or moon to shine on it, for the glory of God gives it light". The fear inspiring presence of the Israelite's God, YHWH, in the Old Testament through this pillar of cloud and fire was a limited foreshadowing of the intimate reunion between God's glory and his people that will come in the end of days. In Revelation 21:3, John hears YHWH speak as he brings his new creative order into reality saying, "And I heard a loud voice from the throne saying, “Behold, the dwelling place of God is with man. He will dwell with them, and they will be his people, and God himself will be with them as their God."
Exodus 13:21-22. By day the Lord went ahead of them in a pillar of cloud to guide them on their way and by night in a pillar of fire to give them light, so that they could travel by day or night. Neither the pillar of cloud by day nor the pillar of fire by night left its place in front of the people.
Exodus 14:24. During the last watch of the night the Lord looked down from the pillar of fire and cloud at the Egyptian army and threw it into confusion.
Numbers 14:14. And they will tell the inhabitants of this land about it. They have already heard that you, O LORD, are with these people and that you, O Lord, have been seen face to face, that your cloud stays over them, and that you go before them in a pillar of cloud by day and a pillar of fire by night.
Deuteronomy 1:33 Who went in the way before you, to search you out a place to pitch your tents in, in fire by night, to shew you by what way ye should go, and in a cloud by day.
Nehemiah 9:12. By day you led them with a pillar of cloud, and by night with a pillar of fire to give them light on the way they were to take.
Nehemiah 9:19. "Because of your great compassion you did not abandon them in the desert. By day the pillar of cloud did not cease to guide them on their path, nor the pillar of fire by night to shine on the way they were to take.
Exodus 40:34-38. "Then the cloud covered the tent of meeting, and the glory of the Lord filled the tabernacle. Moses could not enter the tent of meeting because the cloud had settled on it, and the glory of the Lord filled the tabernacle. In all the travels of the Israelites, whenever the cloud lifted from above the tabernacle, they would set out; but if the cloud did not lift, they did not set out—until the day it lifted. So the cloud of the Lord was over the tabernacle by day, and fire was in the cloud by night, in the sight of all the Israelites during all their travels."
Revelation 21:23-25. "And the city has no need of sun or moon to shine on it, for the glory of God gives it light, and its lamp is the Lamb. By its light will the nations walk, and the kings of the earth will bring their glory into it, and its gates will never be shut by day—and there will be no night there."
Revelation 21:1-4. "Then I saw a new heaven and a new earth, for the first heaven and the first earth had passed away, and the sea was no more. And I saw the holy city, new Jerusalem, coming down out of heaven from God, prepared as a bride adorned for her husband. And I heard a loud voice from the throne saying, “Behold, the dwelling place of God is with man. He will dwell with them, and they will be his people, and God himself will be with them as their God. He will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning, nor crying, nor pain anymore, for the former things have passed away.”
Pillar of Fire (theophany) Wikipedia