It is stated in the Bhagavad-gītā that "Because you are My devotee, you are in full Kṛṣṇa consciousness; therefore I am speaking to you this confidential yoga system, Bhagavad-gītā." Bhakto 'si priyo 'si me (BG 4.3). Rahasyaṁ hy etad uttamam. "The process was there. Now it is lost. So I am speaking to you again the old system because you are My devotee."
Similarly those, or one person who is accepting the version of Arjuna, as Arjuna understood Kṛṣṇa, he is mahājana, and you have to follow him. That's all. If somebody is speaking something against as Arjuna understood, he is not a mahājana, he's a rascal. The simple test. And you go to the Tenth Chapter, Bhagavad-gītā.
Arjuna says, "Kṛṣṇa," sarvam etad ṛtaṁ manye yan vadasi keśava (BG 10.14), "whatever You are speaking, I accept it in toto, without any minus." This is mahājana. Not that according to my whims, I cut something, I accept something. No. One who is accepting the version of Arjuna or Kṛṣṇa, he is mahājana. You can follow him. That's all. It is simple thing.
You haven't got to find out who is mahājana. The mahājana means who is following another mahājana, say follow Arjuna. He is mahājana. (break) . . . to read Bhagavad-gītā and try to understand how Arjuna understood it, then you get . . . and anyone following the footprints of Arjuna, he's mahājana.