The cause for all Enlightenment on mother earth results from our consciousness, our soul atman residing in our heart wanting to reach cosmic end of life at the earliest. Ever since a soul atman starts its cosmic journey when God Almighty (Brahman Hinduism) explodes itself with a big bang, it desires regaining its lost original pure prime pristine primordial form at the earliest.
This becomes possible when life supporting planets like mother earth evolved in cosmic system. Enlightenment can be gained only in human form, never lower forms of life. Before evolving as a human, we as a soul atman manifest form of amoeba, various insects, plants and animals. After completing a cycle of manifesting 7.3 million bodies in insect plant and animal life, the soul atman has a maximum of 1.1 million manifestations in human form to reach state of enlightenment.
Indulging in spirituality as detailed in Bhagavad Gita and Upanishads (independent spiritual treatises) when human beings, serious travelers of spiritual path finally succeed in reaching state of enlightenment, life comes full circle for a soul atman. It finally reaches 8.4 millionth manifestation. The journey of soul atman completes when human beings gained enlightenment.
After becoming a pure soul atman, the need for soul atman to manifest a body ceases to exist. Every soul atman manifests body after another until last trace of dross impurities within remains. The spiritual journey by Mahavira, Gautama Buddha, Jesus Christ and Prophet Mohammed had only one purpose, reach state of enlightenment.
Even Sri Ramakrishna Paramhansa and Maharishi Ramana embarked on a spiritual journey to reach 8.4 millionth manifestation, last in cosmic journey of life.
The goal of human life always was and will be becoming an enlightened one forever. Prime reason why Bhagavad Gita and Upanishads are accorded the highest reverence amongst all sacred paraphernalia existing world over! Enlightenment is gained travelling the inner journey, the journey towards our consciousness existing in heart.
Mahavira (24th Tirthankara of Jainism, preceptor) rightly said the goal of all human beings should be to become a Mahavira, a Jina forever.