Naitoku shinko is to practice without Gohonzon.

In teachings that preceded and followed the Lotus Sutra, we , the
common mortals, and the Buddha are separate beings. So we pray to
Buddha, or beseech Buddha to help us, to save us or to protect us. But
when we come to the Lotus Sutra, we learn that the Buddha is within
us, and that we have to develop our Buddha-nature,which we do by
chanting. We must go inside ourselves for salvation, we must not seek
outside ourselves for help and protection.
Namu-myoho-renge-kyo
includes
ichinen sanzen (all worlds, all things, existing in one being, in
one moment of thought). That means that the world of Buddha also
exists within one being. So we need not search for Buddha or god
outside ourselves. We must look inside and realize that we have
Buddha-nature. This is how one practices
naitoku shinko (seeking faith
without Gohonzon).
NAITOKU SHINKO
By Reverend Raidou Hirota
Translated and edited by Udumbara Foundation volunteers
This is NOT an official site of
the Nichiren Shoshu Shoshin-kai