The definitive way to verify anyone who claims to be “God”

In order to guard against the invention of unauthorized incarnations of God by the fanciful, less intelligent persons, the name of the father of the bona fide incarnation is also mentioned in the authorized revealed scriptures. No one, therefore, can be accepted as an incarnation of the Lord if his father’s name, as well as the name of the village or place in which he appears, is not mentioned by the authorized scriptures. In the Bhagavata Purana the name of the Kalki incarnation, which is to take place in almost four hundred thousand years, is mentioned along with the name of His father and the name of the village in which He will appear. A sane man, therefore, does not accept any cheap edition of an incarnation without reference to the authorized scriptures.

– Srila Prabhupada, Srimad Bhagavatam 2.7.2 purport