vadanti tat tattva-vidas tattvaṁ yaj jñānam advayam brahmeti paramātmeti bhagavān iti śabdyate

vadanti tat tattva-vidas
tattvam yaj jnanam advayam
brahmeti paramatmeti
bhagavan iti sabdyate
"Learned transcendentalists who know the Absolute Truth call this nondual substance Brahman, Paramatma or Bhagavan." (Bhag. 1.2.11)
Absolute knowledge consists of Brahman, Paramatma and Bhagavan. This conclusion is not the same as that of the monists. Srila Advaita Acarya was given the title of acarya because He spread the bhakti cult, not the philosophy of monism. The true conclusion of advaita-siddhanta is not the same as the philosophy of the monists. Here advaita-siddhanta means advaya-jnana, or oneness in variety. Actually Srila Nityananda Prabhu was praising Srila Advaita Acarya through friendly mock fighting. He was giving the Vaisnava conclusion in terms of the Bhagavatam's conclusive words, vadanti tat tattva-vidas. This is also the conclusion of a mantra in the Chandogya Upanisad, ekam evadvitiyam.
A devotee knows that there is oneness in diversity. The mantras of the sastras do not support the monistic conclusions of the impersonalists, nor does Vaisnava philosophy accept impersonalism without variety. Brahman is the greatest, He who includes everything, and that is oneness. As Krsna says in Bhagavad-gita (7.7), mattah parataram nanyat: there is no one superior to Krsna Himself. He is the original substance because every category emanates from Him. Thus He is simultaneously one with and different from all other categories. The Lord is always engaged in a variety of spiritual activities, but the monist cannot understand spiritual variety. The conclusion is that although the powerful and the power are one and the same, within the energy of the powerful there are varieties. In those varieties there is a difference between one's personal self, between types of the same category and between types of different categories. In other words, there is always variety in the categories, which are understood as knowledge, the knower and the knowable. Due to the eternal existence of knowledge, the knower and the knowable, devotees everywhere know about the eternal existence of the form, name, qualities, pastimes and entourage of the Supreme Personality of Godhead. Devotees never agree with the monist's preaching of oneness. Unless one adheres to the conceptions of the knower, the knowable and knowledge, there is no possibility of understanding spiritual variety, nor can one taste the transcendental bliss of spiritual variety.
The philosophy of monism is an adjustment of the Buddhist philosophy of voidism. In a mock fight with Sri Advaita Acarya, Sri Nityananda Prabhu was refuting this type of monistic philosophy. Vaisnavas certainly accept Lord Sri Krsna as the ultimate one, and that which is without Krsna is called maya, or that which has no existence. External maya is exhibited in two phases-jiva-maya, the living entities, and guna-maya, the material world. In the material world there is prakrti (material nature) and pradhana (the ingredients of material nature). However, when one becomes Krsna conscious, material and spiritual variety do not exist. An advanced devotee like Prahlada Maharaja sees everything as one-Krsna. As stated in Srimad-Bhagavatam: krsna-graha-grhitatma na veda jagad idrsam (Bhag. 7.4.37). One who is in full Krsna consciousness does not distinguish between things material and spiritual. He takes everything to be related to Krsna and therefore spiritual. By advaya-jnana-darsana, Srila Advaita Acarya has glorified pure devotional service. Srila Nityananda Prabhu herein sarcastically condemns the philosophy of the impersonal monists and praises the correct nondual philosophy of Sri Advaita Prabhu.