Kundalini spirit is cosmic energy that lay dormant in base of spine. It can be activated only by indulging in spirituality detailed in Bhagavad Gita. Spirituality as in Bhagavad Gita demands seekers practicing absolute celibacy for a minimum period of 12 years in continuation. This leads to awakening of dormant lying kundalini shakti in stages.
The moment this kundalini energy reaches the top the Ajna chakra, Sahasra Pushpa (thousand petalled Lotus) existing in brain behind forehead opens fully. One immediately becomes an enlightened one, a bodhi, a Jina a Mahavira forever.
Holy spirit per se Hinduism means presence of a spirit, consciousness within human beings nay all living beings. Indian spirituality says we are primarily a spirit, a spiritual traveler on its cosmic life cycle of 8.4 million manifestations. To cleanse self of dross impurities within in its lifetime every soul atman, the consciousness within manifests a cycle of 8.4 million bodies.
Presence of soul atman in human body is the real essence of life. Stated otherwise, every soul atman manifests the body again and again. After death of present body based on residual balance of karma at the time of death the released soul atman, spirit would again manifest a new body to start a new cycle of life. This cycle of birth and death continues until practicing spirituality human beings, the soul atman within reaches state of absolute purity.
For soul atman, the Holy Spirit to liberate self from cycle of birth and death forever, full awakening of kundalini spirit is necessitated.
Indulging in Indian spirituality Bhagavad Gita way human beings can finally become an enlightened one forever.
Holy Spirit is the Prana, the sap that is the cause of life on mother earth and in entire cosmos. As per doctrine of Advaita Vedanta propagated by Adi Shankaracharya nothing other than cluster of holy spirits existed in cosmos. This cluster of holy spirits in their pure form is what we called God Almighty, Brahman in all its glory.
We as a human being were not just a manifest physical body. We are primarily the Holy Spirit manifesting human form. Indulging in Bhagavad Gita and also Upanishads (independent spiritual treatises) we can awaken our kundalini shakti to its full potential.