The Abrahamic and other religions have claimed that other universes exist for thousands of years
Source? I'm not aware of their being a significant debate over whether their god could have created more than one universe
They were refered to as Heaven, Hel, Sheol, Paradise, Gehena, etc, ie places not in our universe and thus assumed to be in other universes.
Seven Heavens
Heavens is always plural in Hebrew, with seven levels of heaven, noted in Scripture. The names are: Vilon, Rakia, Shechakim, Zevul, Maon, Machon, and Aravot.
1. Vilon is 'That stretches out the heavens as a curtain (Vilon), and spreads them out as a tent to dwell in.' (Isaiah 40:22[85]) Vilon retires in the morning and comes out in the evening, and renews the work of creation daily. Vilon is the entire universe, going beyond what we can see with telescopes. Vilon is the word for curtain used in the Talmud, but a synonym, doq, pronounced like coke, is the word used in Isaiah 40:22
2. Rakia is where 'God set them in the firmament (Rakia) of the heavens.' (Gen 1:17[19]) This is a reference to the stars, sun, moon, and planets: outer space where the various heavenly bodies move in their prescribed orbits and /or maintain relationships in constellations, solar systems, galaxies, etc. Rakia is the part of the heavens that can be seen.
3. Shechakim is from 'He commanded the skies (shechakim) above and opened the doors of heaven; and He rained down manna upon them to eat.' (Psalm 78:23 [120]) This is where the millstones are located that grind manna for the righteous. His Word is still miraculously feeding us. Shechakim is the atmosphere.
4. Zevul is the location for 'I have surely built you a house of habitation (Zevul), a place for you to dwell in forever.: (1Kings 8:13 [32]) This is the location of celestial Jerusalem and the temple with the heavenly altar where Michael offers a sacrifice. How do we know that Zevul is this place? Because, 'Look down from heaven and behold the habitation (Zevul) of Your holiness and Your glory.' (Isaiah 63:16 [102])
5. Maon is where 'The Lord will command His loving kindness in the daytime and in the night his song shall be with Me.' (Psalm 42:8 [69]) This is where His ministering angels stay, singing in the night. We know that this is heaven because of 'Look down from your holy habitation (Maon) from heaven.' (Deuteronomy 26:15 [46])
6. Machon is the location of the storehouses of snow, rain, hail, whirlwinds, storms, etc. 'The Lord shall open unto you His good treasureÂ…' Deuteronomy 28:12 [45] We know that this is heaven because 'Hear in Heaven, the habitation (Machon) of Your dwellingÂ…' (1Kings 8:39 [58])
7. Aravot is that in which are righteousness, judgment, and charity, the storehouses of life, of peace and of blessing, the spirits of the righteous, with which the Lord will hereafter revive the dead. Those living here include the Ophannim, Seraphim, holy Chayyot, the ministering angels, the Throne of Glory, and the King of the Universe. 'Cast up a highway for Him Who rides upon the clouds (Aravot)Â’ His name is Yah. (Psalm 68:4 [91]) The storehouse of life contains the force of life for all those yet to be born because when God finished creation (Genesis 2:1 [4]) He had made everything that would ever be - including your descendants. The spirits of the righteous are the dead who are sleeping with their fathers.
Notice that the first three represent the universe, the visible night sky and sun, and the atmosphere. These are natural, physical things even when beyond the range of telescopes.
Velon is the highest level of heaven where God's Throne is and it is beyond the stars, beyond our natural universe, while the others are in the natural universe, though described metaphorically.
http://en.wikipedia.org/wiki/Heaven_(Christianity)
Eastern Orthodox cosmology perceives heaven as having different levels (John 14:2), the lowest of which is Paradise. At the time of creation, paradise touched the earth at the Garden of Eden. After the Fall of man, paradise was separated from the earth, and mankind forbidden entry, lest he partake of the Tree of Life and live eternally in a state of sinfulness (Genesis 3:22-24). At his death on the Cross, the Orthodox believe Jesus opened the door to Paradise to mankind again (Luke 23:43), and the Good Thief was the first to enter....
Seven Heavens - Wikipedia, the free encyclopedia
Seven Heavens is a part of religious cosmology found in many major religions such as Islam, Judaism and Hinduism and in some minor religions such as Hermeticism and Gnosticism. The Throne of God is said to be above the seventh heaven in Abrahamic religions.
In Islam:
The seven heavens are the seven layered realms of the spiritual upper world where generally angels and other spiritual beings such as Paradise and Hell and the souls of the prophets exist. The seven heavens are part of Al-Ghayb (Arabic: الغيب* The Unseen), the occult or unseen universe in Islamic cosmology as opposed to Al-Shahadah (Arabic: الشهادة* The Seen), the universe we know. Some scholars have said that the original meaning of the Arabic word سماوت is the hypothetical multiverse or "worlds of space and time" and not "sky" as is used in Modern Arabic.