How many levels of enlightenment are there?
According to the flower adornment sutra, there are altogether 53 level of enlightenment. When practitioner reached the 11th level of the 53 is known as true enlightenment in view of bodhi actualization. Stream enterer, one returner till arahat achieved a stage of enlightenment out of samsaric cycle but they did not realize bodhi and will eventually attain supreme enlightenment as well.
according to TienTai school's 52stages of bodhisattvas +1 Buddha :
十住——破十品无明惑 Ten Dwelling stage bodhisattva's= start to work on the 42 pieces of ignorance. 破一品无明,证一分法身
十地——破四十品无明惑 <--Pure land beings are somewhere here, ie 8th Ground bhumi!
Ten Faith -- 十信——初信——断见惑，伏思惑 --- First faith --sever all Eighty-Eight Deluded Viewpoints, conceal Cognitive Delusions.
——七信——断思惑 ----7th faith sever all Cognitive Delusions.
——八信——伏尘沙惑 ----8th faith conceal the illusive affliction and temptation through the immense variety of duties in saving sentient beings.
——九信——断十品尘沙惑---9th faith sever ten illusive afflictions.
——十信——断二十品尘沙惑，伏无明惑 --10th faith sever all the twenty illusive afflictions, while concealling the confusive unknown.
十住——破十品无明惑 within Ten Dwelling stages --- realised ten levels of confusive unknown.
十行——破二十品无明惑 within Ten Behavioral Activities stages ---realised twenty levels of confusive unknown.
十回向——破三十品无明惑 within Ten Transference stages ---realised thirty levels of confusive unknown.
十地——破四十品无明惑 within Ten Stages ---realised fourty levels of confusive unknown.
等觉——破四十一品无明惑 near–perfect enlightenment---realised fourty-one levels of confusive unknown.
妙觉——破四十二品无明惑 wonderful Enlightenment ---realised fourty-two levels of confusive unknown.
佛果——洗净无明习气——成就佛果 Ultimate Enlightenment ---All knowing!
also depend on which of the four teaching u study. the above is from 圆教Complete teaching.
藏Collective——教如莲花初生正化二乘凡夫，兼化钝根菩萨Like a lotus newborn，properly upgrade the 2 vehicles and unite the dully rooted bodhisattva。
通Common——钝根通前藏教，利根通后别圆，正化菩萨兼化二乘凡夫 properly upgrade the junior bodhisattvas，and unite the 2 vehicles。
别Special——别前二教，别后圆教，正化界外钝根菩萨无明惑重properly upgrade the dully rooted bodhisattva of other doors，that have strong doubts。
圆 Complete——圆信 Complete faiths，
圆悟 Complete realisation，
圆修 Complete cultivation，
圆证 Complete verification，
正化界外利根菩萨无明惑轻 properly upgrade the well-established bodhisattvas，doubts are light，
仗自力修 Self-power cultivating，
难中之难 which is difficult。
Common teachings have Ten Stages.
1干慧地：未有理水，故得其名。即外凡位，与藏教五停心、总别等三位齐。Dry wisdom stage.
2性地：相似得法性水，伏见思惑。即内凡位。与藏教四善根齐。Nature stage. 3八人地。Saint stage.
4见地：此位与八人地入无间三昧，断三界八十八使见尽，发真无漏，见真谛理。与藏教初果齐。4th Behold Stage is equivalent to Collection teaching's 1st arahant stage (stream entry). Eliminated the Eighty-Eight Deluded Views.
5薄地：断欲界九品思前六品。与藏教二果齐。5th Shallow Stage is equivalent to 2nd Stage ('once-returner'). Eliminated 6 of the 9 degrees of cognitive delusions.
6离欲地：断欲界九品思尽。与藏教三果齐。6th is equivalent to 3rd 'never-returner'. Eliminated all 9 degrees of cognitive delusions.
7已办地：断三界见思惑尽，但断正使，不能侵习，如烧木成炭。与藏教四果齐。声闻位齐此。7th of Common teaching is equivalent to Arhathood of Collection teaching. Eliminated both Deluded Views & cognitive delusions of Samsara.
The four stages of enlightenment in Buddhism are the four progressive stages culminating in full enlightenment as an Arahant, which an average, instructed person can attain in this life. The four stages are Sotapanna, Sakadagami, Anagami and Arahant. For those that have destroyed greed and hatred (in the sensory context) with some residue of delusion, are called anagami (non-returner). Anagamis will not be reborn into the human world after death, but into the heaven of the Pure Abodes, where only anagamis live. There, they will attain full enlightenment.
According to Buddhist cosmology, you get reborn into any of the planes of existence according to your karma. Karmic law functions whether or not you believe in it.
It's like how even if you didn't take the precept vows, you are still accountable for your actions. It doesn't mean that a person who didn't vow to keep the 1st precept can go out and kill without karmic consequence.
Of course, if you don't subscribe to Buddhist beliefs then you may choose not to accept that those planes of existence are as described in the sutras. One may even choose to disbelieve karma. This bit is up to the individual.
As said before, according to Buddhist understanding, beings are born into particular realms according to their karma. In this sense, I don't see why a non-Buddhist who has gained enlightenment, purified his mind and perfected morality to a certain degree cannot go to the Pure Abodes. Just because the Pure Abodes have been described as 'celestial realm of a Buddha or Bodhisattva', does not exclude anyone who was non-Buddhist while in human form. As long as one is karmically in alignment with that realm, he can be reborn there.
The "Pure Abodes"; a name given to a group of Brahma-worlds - the five highest Rūpa worlds - consisting of
Akanitthā (E.g., D.iii.237).
There anāgāmī are born, and there they attain arahantship; such anāgāmī are divided into twenty four classes (See, e.g., KhA.182f.; of. PSA. 319; Vsm.710)
Bodhisattas are never born there (SNA.i.50; BuA.224).
The Suddhāvāsā are described as buddhānam khandhāvāratthānasadisā. Sometimes, for asankheyyas of kappas, when no Buddhas are born, these worlds remain empty (AA.ii.808; cf. MA.i.30).
The Buddha is mentioned as having visited the Suddhāvāsā (E.g., D.ii.50). When a Buddha is about to be born, the inhabitants of the Suddhāvāsā insert a knowledge of the signs of a Great Being in the Vedas and teach this among men in the guise of brahmins, calling such knowledge buddhamanta. Men learn it and are thus able to recognize a Great Being (MA.ii.761; SNA.ii.448). The inhabitants of the Suddhāvāsā know how many Buddhas will be born in any particular kappa by observing the number of lotuses which spring up on the site of the Bodhi-pallanka when the earth gradually emerges after the destruction of the world (DA.ii.411). It is the Suddhāvāsā Brahmās who provide the four omens which lead to a Bodhisatta's renunciation in his last lay life. See, e.g., DA.ii.455f.
In Buddhism, an anāgāmi (Sanskrit and Pāli for "non-returning") is a partially enlightened person who has cut off the first five chains that bind the ordinary mind. Anagami-ship is the third of the four stages of enlightenment.
The Pali terms for the specific chains or fetters (Pali: saṃyojana) of which an anagami is free are:
Sakkāya-diṭṭhi: Belief in self
Vicikicchā: Skeptical doubt
Sīlabbata-parāmāsa: Attachment to rites and rituals
Kāma-rāga: Sensuous craving
Byāpāda: Ill will
The fetters from which an anagami is not yet free are:
Rūpa-rāga: Craving for fine-material existence (the first 4 jhanas)
Arūpa-rāga: Craving for immaterial existence (the last 4 jhanas)
Anagamis are at an intermediate stage between sakadagamis and arahants. Arahants enjoy complete freedom from the ten fetters.
Attaining the state of non-returner is portrayed in the early texts as the ideal goal for laity