Faith, in the matter you ask about, is of three kinds. It belongs to embodied beings and is 'born of their own nature'. The dispositions formed by acts of merit and the like in earlier births lie latent and become manifest at the time of death; this is what is called one's nature, and the faith that arises from it is 'born of nature'. Faith of the quality of sattva turns toward the worship of the gods. Faith of the quality of rajas turns toward the worship of yakshas and rakshasas. Faith of the quality of tamas turns toward the worship of departed spirits and ghosts. Hear, then, this threefold faith as it is now described.

The Blessed Lord spoke. Of all the embodied, faith is of three kinds, and it is born of one's own nature. One's own nature is one's peculiar disposition; it is the particular relish, occasioned by earlier impressions; where there is relish, there faith arises. For faith is a haste toward a means, preceded by the trust 'this accomplishes what I hold dear'. The impress, the relish, and the faith are properties of the self, born of the conjunction with the qualities. The begetters of those properties of the self, the impress and the rest, are the traits, present in the body, the senses, the inner organ, and the objects, definable solely by their effect, the qualities sattva and the rest; that is, they are born of the experience of the body and the rest joined with the qualities sattva and the rest. Therefore this faith is of three kinds, sattvic, rajasic, and tamasic. Hear this faith; that is, hear the nature of which that faith is. This is the meaning.

This is a brief sub-gloss. For a fuller reading of this verse, see Madhusūdana, Śaṅkara, or Rāmānuja above.

Therefore Krishna speaks by dividing it up, with 'threefold' and so on.