This is based on an ancient Reddit post I made many kalpas ago. May the Syncretic God forgive me for any mistakes I make.
Note that this article presupposed a predominantly Sunni Islamic view, and a Mahayana/Vajrayana Buddhist View.
Let us compare some parallels:
On the plurality of Messengers
— Infinite Buddhas. According to the Bhadrakalpika Sūtra, we on Earth are slated for 1002 fully enlightened Buddhas in this Fortunate Kalpa alone. How lucky we are! We are currently 4 Buddhas in.
— 124,000 Prophets in Islam (or 25,000+ Prophets). Alot of Prophets. Sent to all peoples in the world.
On the interstitial periods
— Periods of time with no Buddhas (Dark Kalpa).
— Periods of time with no Prophets (Ahl al-Fatrah).
On non-human intelligent life, their religions, and the Devil
— Devas are mortals, don’t worship them.
— Djiins are mortals, don’t worship them.
— King Mara is a deva who is the Devil.
— Iblis is a Djinn who is the Devil.
— The Maras are devas who follow King Mara.
— The Shaitans are Djinns who follow Iblis.
— Devas are not necessarily Buddhist. Many have to be converted to Buddhism. Vast majority are ignorant of the Dharma or are the purview of other Buddhas in other trichiliocosms.
— Djinns can be Jewish, Christian, Muslim or other (that’s why they need to be converted to Islam).
On the Degeneration of the True Faith
— In Buddhism, the Dharma is taught by a perfectly enlightened Buddha, but then degenerates over time until only Buddhist culture is left, and eventually, even that is forgotten. When this happens, a new Buddha will arise and spin the Wheel of Dharma once more.
— In Islam, eventually, a divinely revealed faith will become corrupted, and a new Messenger is sent by God to teach Islam (both Judaism and Christianity— and potentially more— are considered corrupted versions of Islam).
On the Buddhas/Enlightened-Beings & Messengers/Prophets
— Prophets VS Messengers. Prophets are sent by God to serve as moral paragons and to teach people. But some Prophets are Messengers, which bring with them Divinely Revealed Messages (that usually then become a major scripture; such as the Torah, the Psalms, the Gospel, and the Qur’an— though in Islam, all versions of these are corrupt save the Qur’an, which is the latest divinely revealed message).
— A Perfectly Enlightened Buddha is the only being capable of preaching the True Dharma, and only in a period of time around which they existed in the world to turn the Wheel of Dharma do the Dharma persists, no matter who propagates it.
In periods of time in which the Dharma is absent, Pretyekabuddhas (self-enlightened Buddhas) do occasionally arise, but they are incapable of teaching the Dharma because they simply lack the compassion/insight/intellectual resources required to do so. A Pratyekabuddha can give moral teachings, but cannot help others attain Enlightenment, and they do not leave behind a Sangha (Monastic Order).
A Buddha doesn’t magically attain knowledge or skill. A pretyekabuddha lacking the right conditions (either in the time period, the culture, or even the language) cannot express the Buddha-Dharma to sentient beings, and thus do not fulfill the role of a perfectly enlightened Buddha, incapable of turning the Wheel of Dharma.
Likewise, Arahants (technically a lesser kind of Pratyekabuddha) also are not capable of transmitting the manifold Dharma.
— Iddhis (supermundane powers that can be developed as a side-effect of practicing the path; though it should not be the goal, as it’s considered not True Dharma).
— Karamat (‘miracles’ performed by Saints. Like Tay al-Arzor or mystical teleportation).
On the Multiverse
— Allah, Lord of Worlds
— Contrasted with Buddhist conception of the Great Trichiliocosm (1 billion worlds), and there are infinite Trichiliocosms, filled with many different kinds of life. Each Trichiliocosm has a single Supremely Enlightened Buddha (though there are infinite Buddhas everywhere, all the time).
— In Buddhism, Buddha-Nature vs Aggregates [cause & effect phenomenon, compounded phenomenon]
— And in Islam, especially Sufism, Rūḥ (Spirit) vs Nafs (Souls).
In Buddhism, the Buddha-Nature or Dharma-Nature is the all-pervading nature, or “reality as it is, the way things are, phenomenon as it is, devoid of delusions”. This Dharma-Nature as present in a sentient being is Buddha-Nature (well, the potential for it, specifically).
In Islam, the Ruh are myriad phenomena. Sometimes identified as Angels, sometimes as the spirit in human beings, and sometimes as that which animates inanimate matter.
In addition, Buddha-Nature is also the nature of phenomenons, and Rūḥ is what allows Nafs to work.
Thus as described in Islam in Perspective, Rūḥ is Nafs in one sense, but yet they are not. The Rūḥ drives the Nafs (the souls, which are our desires and sensory perceptions; in essence our psychic organs), but the Rūḥ is apart of it.
Just as Buddha Nature is both the workings of phenomena and yet it is not (Nirvana is Samsara, Samsara is Nirvana).
In essence, we have the embryonic form of a Buddha within us (tathāgatagarbha— the embryonic Buddha) that must be developed so that we can become Buddhas (Buddha-dhatu— the Buddha Nature/Realm/Substrate). The potential for Enlightenment is there…we just have to perfect it.
In Zen, one must have faith that they have a Bodhi-Mind (a Buddha Nature) in order to realize enlightenment.
In Islam, Rūḥ is what God give us, so that we can come to know him, and to perfect it.
The two terms have that inherent meaning of being transcendental, as according to Buddhist, every Buddha expounded the same Dharma, from innumerable universes ago to now. According to Muslims, every Prophet expounded the same Islam (including Adam, Noah, Moses, Jesus, etc).
Buddhism denies Reincarnation (Metempsychosis). In Buddhism, the doctrine is Rebirth, which is “re-becoming”, not reincarnating, as it’s best to see all of our infinite lives as a singular life (as a result of phenomenon dictated by cause & effect).
In Buddhism, every moment is a rebirth, because it denotes the Mindstream changing and moving; bodily death is a bigger change (a larger wave made by the coursing river of Mind phenomenon), but not that different than the moment to moment experience we already have. Some call sleep the little death for this reason.
Everyday you live without Enlightenment (realization of Buddha-Nature) is already death anyway; thus Mara (the Devil), and the condition he embodies, is often called the Spiritual Death.
Buddhist Phenomenology denies a conventional soul (that is, a soul conceived of as another body or an object that one could mistakenly fixate their ego upon), but it believes in the Buddha-Nature (which is the foundational mind, absence delusions, and also phenomenon as it is). And this is because things being alive and having a soul, are one and the same (similar to the Jewish conceptions of the soul being indivisible with body, and arisen together with it).
Thus in Buddhism, a sentient being is an aggregate of different causes & effects (form, perception, sensation, wilful intent, consciousness), none of which have independent existence. Similar to the Nafs.
The Five Aggregates in Buddhism are the invariable constituents of a sentient being’s experience in a given moment.
Some things are just more alive than others (animals are more alive than plants, which are more alive than ordinary matter).
In Buddhist theology, the totally deluded (Icchantikas) have lost their Buddha-Nature entirely and can never attain Nirvana (but their Buddha-nature is recoverable if they are able to regain a small measure of a conscience).
Icchantikas is actually the closest equivalent to the Hebrew Gehenna or post-eschatological damnation present in all Abrahamic Religion.
The ultimate fate of Icchantikas is questionable. My own tradition at least, argues that Icchantikas are eventually dissolved into Qi (annihilated).
Thematically at least, the Buddhist Naraka (Hellworlds) are closer in conception to Sheol or the Islamic Barzakh (the Grave), since Naraka is not actually damnation. Narakas are considered proper rebirths. Being born in Naraka is not damnation. The Icchantika is however, a damning fate.
For a true transitory or purgatorial existence, in Buddhism that would be the Bardo (the fluid intermediate state between lives; which can be experienced as a hallucinatory nightmare for the deceased).
On God & Angels
Say, “He is Allah , [who is] One, Allah , the Eternal Refuge. He neither begets nor is born, Nor is there to Him any equivalent.”
— Surah Al-Ikhlas [112:1-4]
“There is, O monks, an Unborn, Unoriginated, Uncreated, Unformed. Were there not, O monks, this Unborn, Unoriginated, Uncreated, Unformed, there would be no escape from the world of the born, originated, created, formed. Since, O monks, there is an Unborn, Unoriginated, Uncreated, Unformed, therefore is there an escape from the born, originated, created, formed. What is dependent, that also moves; what is independent does not move. Where there is no movement, there is rest; where rest is, there is no desire; where there is no desire, there is neither coming nor going, no ceasing-to-be, no further coming to be. Where there is no ceasing-to-be, no further coming-to-be, there is neither this shore [this world] nor the other shore [Nirvana], nor anything between them.”
— Shakyamuni Buddha, Udana Nikaya (viii: 3)
More specifically, in Buddhism, you can conceptualize the Adi-Buddha as the primordial Buddha inherent in all things. Specifically, Adi-Buddha is identified as Vairocana, or the Dharmakaya (Truth Body) of Shakyamuni Buddha. Dharmakaya is representational of Dharma-Nature, in a manner very much akin to MALAKH YHWH (Angel that is the Lord in the Bible) sort of entity. Effectively God, but still not God (Dharma-Nature pervades the whole, but is not the whole. The closest you will find to a statement on the Uniqueness of God in Buddhism).
In Islam, none of the Angels have Free Will, being extension of God’s Will. Again, a functional god (in terms of how God interacts with the world. It was not God who directly spoke to the Prophet Muhammad, but instead, he used Gabriel as an intermediary to communicate his message. Why is this intermediary necessary? Because that is how God acts in the world; admittedly, this draws a bit from the Esoteric Kabbalistic conception of what Angels are— as Tasks of God, rather than from Islam).
A Buddha is like such a process.
Peace be upon you.