One must not only think that he is Brahman, but must act like Brahman. One who only thinks himself Brahman is an impersonalist. And one who acts like Brahman is the pure devotee
SB Canto 1
Thus annihilating the gross body of five elements into the three qualitative modes of material nature, he merged them in one nescience and then absorbed that nescience in the self, Brahman, which is inexhaustible in all circumstances.
All that is manifested in the material world is the product of the mahat-tattva-avyakta, and things that are visible in our material vision are nothing but combinations and permutations of such variegated material products. But the living entity is different from such material products. It is due to the living entity's forgetfulness of his eternal nature as eternal servitor of the Lord, and his false conception of being a so-called lord of the material nature, that he is obliged to enter into the existence of false sense enjoyment. Thus a concomitant generation of material energies is the principal cause of the mind's being materially affected. Thus the gross body of five elements is produced. Mahārāja Yudhiṣṭhira reversed the action and merged the five elements of the body in the three modes of material nature. The qualitative distinction of the body as being good, bad or mediocre is extinguished, and again the qualitative manifestations become merged in the material energy, which is produced from a false sense of the pure living being. When one is thus inclined to become an associate of the Supreme Lord, the Personality of Godhead, in one of the innumerable planets of the spiritual sky, especially in Goloka Vṛndāvana, one has to think always that he is different from the material energy; he has nothing to do with it, and he has to realize himself as pure spirit, Brahman, qualitatively equal with the Supreme Brahman (Parameśvara). Mahārāja Yudhiṣṭhira, after distributing his kingdom to Parīkṣit and Vajra, did not think himself Emperor of the world or head of the Kuru dynasty. This sense of freedom from material relations, as well as freedom from the material encagement of the gross and subtle encirclement, makes one free to act as the servitor of the Lord, even though one is in the material world. This stage is called the jīvan-mukta stage, or the liberated stage, even in the material world. That is the process of ending material existence. One must not only think that he is Brahman, but must act like Brahman. One who only thinks himself Brahman is an impersonalist. And one who acts like Brahman is the pure devotee.