"SGI members are all Buddhas" -- SGI Teaching
"Suppose someone declares that he has already attained the most perfect enlightenment. When asked for the reason, [he replies] 'It is because [the tathagata teaches that all sentient beings] have Buddha-nature. Since who ever is in possession of the Buddha-nature should have already attained the most perfect enlightenment, [I declare] that I have attained enlightenment now.' It should be understood that such a person is guilty of the pârâjikas [worst offense possible, punishable by expulsion from the Buddhist order]." -- Nirvana Sutra
According to the Nirvana Sutra which Nichiren calls our "true good friend", SGI members in calling themselves Buddhas are guilty of the worst offense possible.