Caitanya Mahāprabhu confirms, yei kṛṣṇa-tattva-vettā sei guru haya (CC Madhya 8.128). One who has understood Kṛṣṇa as the supreme controller, the Supreme Person, the supreme maintainer, and everything the supreme, ultimate, then he can become guru. Otherwise, don't try to become guru. Impersonalists, half-understood, partial-understood, he cannot become guru. This is the Caitanya Mahāprabhu's formula. Therefore, first of all try to understand Kṛṣṇa. You will understand in such a way that you can refute all others' argument, all others' opposition. There are so many opposing elements. Then you are guru. Otherwise you cannot become a guru. Guru is not so teeny thing or trifle thing that everyone becomes Guru Mahārāja. No. That is not guru. Sa mahātmā. . . Vāsudevaḥ sarvam iti sa mahātmā sudurlabhaḥ (BG 7.19).
So their theory, this atheistic theory, is aparaspara-sambhūtam. It has taken by mechanical arrangement. Mechanical. . . Kim anyat kāma-haitukam (BG 16.8). Kāma. Just like kāma—a man, a woman becomes lusty, and there is sex, and there is production. So they say like that. The production is like that. There is no other plan. But there is a big plan. That they do not know. The plan is: yadā yadā hi dharmasya glānir bhavati bhārata, tadātmānaṁ sṛjāmy aham (BG 4.7). That is plan. But these rascal, this atheist class, they say, kim anyat kāma-haitukam: "Only lusty desires, that is the only reason. That is the only cause." The atheist class think like that, that "This birth is taking place due to our lusty desires, but we do not want to take responsibility. Then kill him."