The Lotus Sūtra enjoins us to give up the provisional teachings, saying that with faith we can enter the Way to Buddhahood. The Nirvana Sūtra preached last in the śāla forest states that there are numerous ways to get the seed of Buddhahood, but as faith in the Three Treasures include all those ways, it is faith in the Three Treasures that matters most. The basic way to Buddhahood thus lies in faith.
Hokke Daimoku Shō, Treatise on the Daimoku of the Lotus Sūtra, Writings of Nichiren Shōnin, Faith and Practice, Volume 4, Page 36-37