The mantra is called the ishta, which means incarnation. The name of a deity can be Iswara Saghuna Brahman or an incarnation of God. In between there is something interesting and the most secret part of the mantra: the beja,. This comes from Tantra, from Kashmirish Ivesm. And this is what connects. It usually stands for the Divine Mother, for Shakti. We should call it avatara yoga. Very powerful, most powerful way for spiritual practice and liberation, incarnation.