KAI TOUTO is adverbial in this sentence, "and especially", and refers to the verb, SESWSESMENOI, "you are saved." It serves the same function in 3 John 5. See Wallace, Greek Grammar Beyond the Basics, p.334-335.
Read "For you are rescued by benevolence through faith, and especially not because of yourselves." KAI TOUTO points to you being saved/rescued not because of anything deserving in you, drawing the obvious conclusion that it is because of the work of Christ.