Reading DT Suzuki's "Buddha of Infinite Light" may help clarify this. Shin is either the apex or a degeneration of Pure land Buddhism, depending on how you look at it. Whatever the case may be, Shin is part of Pure Land (PL) Buddhism.
Shin relies completely on Amida's vows to deliver all beings to the PL. Earlier PL traditions combine self-power with other-power to ensure arrival in the PL. It's no different with the Catholic and Protestant arguments on faith vs. works. Catholics maintain that one must cooperate with the grace of God to ensure salvation. So too must PLers cooperate with Amida's vow to ensure rebirth in the PL. This cooperation entails recitation/mindfulness of the the Buddha, following precepts, etc. In short, one must have enough merit to be reborn in the Land of Ultimate Bliss, as the short sutra reads. ("Sariputra, one cannot be born in this land with a lack of merit or wholesome roots." Thich Nhat Hanh's translation)