Reincarnation and God-realization

Evolution & Involution
According to Baba, each soul pursues conscious divinity by evolving: that is, experiencing itself as form in seven "kingdoms" — stone/metal, vegetable, worm, fish, bird, animal, and human. The soul gathers sanskaras (impressions) in each form, and these impressions lead to further evolution expressed by taking new, more complex forms. With each new form, increasing consciousness is gained until the soul experiences and discards forms from all the evolutionary kingdoms. The final form of the soul's evolution is the human form. Only in the human form can the soul experience its own divinity by entering into involution, through which it gradually eliminates all impressions that cause the appearance of separateness from God.
- Faith & Philosophy of Zoroastrianism, Meena Iyer


Reincarnation and God-realization
Baba asserts that in the human form, the soul becomes subject to reincarnation, the "involuntary process of association and disassociation of consciousness". The purpose of reincarnation is to provide the opportunity for liberation from illusion. The soul reincarnates innumerable times in all conditions of life encompassing the whole range of human experience (e.g. man/woman, rich/poor, powerful/weak, etc.). Through the experience of opposites, sanskaras gradually grow fainter and scarcer. 

Meher Baba describes the process of God-realization this way: From out of the depth of unbroken Infinity arose the Question, "Who am I?" And to that Question there is the answer, "I am God!"

Meher Baba described heaven and hell as transitory and illusory states between incarnations: The states of heaven and hell are nothing but states of intensive experiences of the consciousness of the soul, experiencing either of the predominant counterparts of the opposite impressions while the soul is dissociated from the gross human body or form
http://en.wikipedia.org/wiki/Meher_Baba

Spiritual Poetry 
I died as a mineral and became a plant,
I died as plant and rose to animal,
I died as animal and I was Man.
Why should I fear? When was I less by dying?
Yet once more I shall die as Man, to soar
With angels bless’d; but even from angelhood
I must pass on: all except God doth perish.
When I have sacrificed my angel-soul,
I shall become what no mind e’er conceived.
Oh, let me not exist! for Non-existence
Proclaims in organ tones,
To Him we shall return.
-Rumi