Srimad-Bhagavatam: Canto 8 - Chapter 1 - Verse 13
स विश्वकाय: पुरुहूत ईश:सत्य: स्वयंज्योतिरज: पुराण: ।धत्तेऽस्य जन्माद्यजयात्मशक्त्यातां विद्ययोदस्य निरीह आस्ते ॥ १३ ॥
sa viśva-kāyaḥ puru-hūta-īśaḥsatyaḥ svayaṁ-jyotir ajaḥ purāṇaḥdhatte ’sya janmādy-ajayātma-śaktyātāṁ vidyayodasya nirīha āste
The entire cosmic manifestation is the body of the Supreme Personality of Godhead, the Absolute Truth, who has millions of names and unlimited potencies. He is self-effulgent, unborn and changeless. He is the beginning of everything, but He has no beginning. Because He has created this cosmic manifestation by His external energy, the universe appears to be created, maintained and annihilated by Him. Nonetheless, He remains inactive in His spiritual energy and is untouched by the activities of the material energy.
Śrī Caitanya Mahāprabhu says in His Śikṣāṣṭaka, nāmnām akāri bahudhā nija-sarva-śaktiḥ: the Supreme Personality of Godhead has many names, which are all nondifferent from the Supreme Person. This is spiritual existence. By chanting the Hare Kṛṣṇa mahā-mantra, consisting of names of the Supreme Lord, we find that the name has all the potencies of the person. The Lord’s activities are many, and according to His activities He has many names. He appeared as the son of mother Yaśodā, and also as the son of mother Devakī, and therefore He is named Devakī-nandana and Yaśodā-nandana. Parāsya śaktir vividhaiva śrūyate: the Lord has a multitude of energies, and therefore He acts in multifarious ways. Yet He has a particular name. The śāstras recommend which names we should chant, such as Hare Kṛṣṇa, Hare Kṛṣṇa, Kṛṣṇa Kṛṣṇa, Hare Hare. It is not that we have to search for some name or manufacture one. Rather, we must follow the saintly persons and the śāstras in chanting His holy name. Although the material and spiritual energies both belong to the Lord, He is impossible to understand as long as we are in the material energy. And when we come to the spiritual energy, He is very easy to know. As stated in Śrīmad-Bhāgavatam (1.7.23): māyāṁ vyudasya cic-chaktyā kaivalye sthita ātmani. Although the external energy belongs to the Lord, when one is in the external energy (mama māyā duratyayā) He is very difficult to understand. However, when one comes to the spiritual energy, one can understand Him. Therefore in Bhagavad-gītā (18.55) it is said, bhaktyā mām abhijānāti yāvān yaś cāsmi tattvataḥ: one who wants to understand the Supreme Personality of Godhead in reality must take to the platform of bhakti, or Kṛṣṇa consciousness. This bhakti consists of various activities (śravaṇaṁ kīrtanaṁ viṣṇoḥ smaraṇaṁ pāda-sevanam/ arcanaṁ vandanaṁ dāsyaṁ sakhyam ātma-nivedanam), and to understand the Lord one must take to this path of devotional service. Even though the people of the world have forgotten God and may say that God is dead, this is not a fact. One can understand God when one takes to the Kṛṣṇa consciousness movement, and thus one can be happy.