We have a form because our father has a form. So why should the supreme father not have a form? In the Bhagavad-gītā (14.4) Kṛṣṇa says, ahaṁ bīja-pradaḥ pitā: “I am the seed-giving father of all beings.” The Christians also believe that God is the supreme father. If the sons all have forms, how is it that the father has no form? We cannot be born of a father who is formless. Īśvaraḥ paramaḥ kṛṣṇaḥ sac-cid-ānanda-vigrahaḥ: “Kṛṣṇa is the supreme controller and the cause of all causes, and He possesses an eternal form of knowledge and bliss.” (Brahma-saṁhitā 5.1) Vigraha means “form.” If God is the cause of all causes, the creator, and He is creating all these forms, how can He be formless?
God has a form, but it is not a form like ours. His form is sac-cid-ānanda, but ours is just the opposite. God’s form is sat, eternally existing, while man’s form is asat, temporary. God’s form is cit, full of knowledge, but ours is acit, full of ignorance. And His form is full of ānanda, bliss, but ours is full of nirānanda, misery. It is only because we cannot conceive of a form so different from ours that sometimes it is said God is nirākāra, without form.
God’s form is transcendental. That means His body is not material but spiritual. His form is of a different nature than that to which we are accustomed. In the Vedas it is said that God sees but that He has no eyes. This means that God’s eyes are unlike ours-they are spiritual, not material. We can see only so far, whereas God can see everything because He has eyes everywhere. His eyes, His form, His hands and legs are of a different nature than ours.
Unlike our knowledge, Kṛṣṇa’s knowledge is unlimited. As He says in the Bhagavad-gītā (7.26), “I know past, present, future-everything.” Earlier (Bhagavad-gītā 4.5) He reminds Arjuna, “Both you and I have taken many births. I remember them all, but you have forgotten them.” Thus there is no limit to His knowledge. His knowledge, His body, and His happiness are completely different from our knowledge, body, and happiness. Therefore it is only out of ignorance that some people say the Absolute Truth is nirākāra, formless.
Thinking that God has no form is just imagination. It is material thought. We have a form, so He must have a form, though not a form like ours. Only fools think God is ultimately formless. Kṛṣṇa declares this in the Bhagavad-gītā (7.24): avyaktaṁ vyaktim āpannaṁ manyante mām abuddhayaḥ. “Unintelligent men think that I was impersonal before and have now assumed this personality.” In another place in the Bhagavad-gītā, those who deride the personal form of God are called mūḍhās, or asses. God certainly has a form, but His form is entirely different from ours. That is the real understanding of nirākāra.
(extract from a book written by His Divine Grace A.C Bhaktivedanta Swami Prabhupāda)