One of the four things required in order to obtain the Lotus Sutra is firmness of faith. Firmness of faith here is referring to the kind of faith and practice that is steady and always growing. This is a faith that is a manifestation of the confidence in the truth of the Lotus Sutra. This steadiness of faith is not stagnant but is constantly expanding. You might think of it as entering a positive feedback loop, where faith begins to actually be a motivating force in practice. Initially as we begin to practice we might not have absolute faith in the Lotus Sutra and what we are doing or even if it works. So our practice at first is about building faith based upon changing theory into actual lived experiences. The more we practice the stronger our faith becomes. As our faith grows it becomes the motivation for practice and is no longer the aim of practice.