As per Lord Krishna in Bhagavad Gita Brahman, God Almighty always was formless (Nirakaar). Brahman also was Nirguna, without an attribute.
The Nirakaar in form of God is believed by those practicing spirituality, never by religious practitioners who believed in Sakaar form of God (having a form).
Bhagavad Gita is all about spirituality indulging in which human beings reached God himself. As per Bhagavad Gita we are primarily a spirit, consciousness that manifest in our heart as soul atman. If we are a spirit then God Almighty, Brahman also is a spirit.
God is a cluster of primordial cosmic energy, the sum total of all souls’ atmans in cosmos in their pure form. This cluster of pure energy at the time of origin of cosmos is the size of half a thumb. Brahman, God Almighty at the time of occurrence of big bang is the size of half a thumb.
Spiritual journey, journey towards our inner self is reaching the spirit existing in our heart. The total concept of spirituality is based on faith prime reason why science cannot step into spirituality. Our belief in god, our belief in world of souls’ atmans is the prime reason for undertaking spiritual journey. Spiritual journey is always a journey into the unknown.
Even when a spiritual seeker like Sri Ramakrishna Paramhansa or Maharshi Ramana completes ones spiritual journey, one never knows what to find at the end of journey.
My personal pursuit of God started six years of age. In 1993 37 years of age when I had a Sakshat Darshan of God Almighty I did not know what I had achieved or what would be my step further. I just flowed along the path. As instructed by God I continued my spiritual routine of life even after reaching stage of self realization, god realization.
From the very beginning of life I believed in Nirakaar form of God. I never believed Lord Krishna represented God Almighty. I always believed that every single human being was only an instrument of God Almighty, doing his bidding all the time. After reaching stage of self realization my surmise was proved right. I could now distinguish between stature of Lord Krishna and man gods like Mahavira, Gautama Buddha Jesus Christ and Prophet Mohammed.
All these man gods from the very beginning believed in formless form of god.