"The true teaching is the fundamental requirement of a perfect organization" -- Nirvana Sutra

"Of organizations, there are three kinds.  First there are those that are
organized on the basis of the power, wealth or authority of great leaders. 

Second, there are those that are organized because of its convenience of the
members, which will continue to exist as long as the members satisfy their
conveniences and do not quarrel. 

Third, there are those that are organized with some good teaching as its
center and harmony as its very life. 

Of course, the third or last of these is the only true organization, for in
it the members live in one spirit, from which the unity of spirit and
various kinds of virtue will arise.  In such organization there will prevail
harmony, satisfaction and happiness. 

Enlightenment is like rain that falls on a mountain and gathers into
rivulets that run into brooks, and then into rivers which finally flow into
the ocean. 

The rain of the sacred teaching falls on all people alike without regard to
their condition or circumstances.  Those who accept it gather into small
groups, then into organizations, then into communities and, finally find
themselves in the great Ocean of Enlightenment. 

The minds of these people mix like milk and water and finally organize into
a harmonious Sangha. 

Thus, the true teaching is the fundamental requirement of
a perfect organization and, as mentioned above, it is the light which
enables people to recognize one another, to become adjusted to one another
and to smooth out the rough places in their thinking. 

Thus, the organization that is formed on the perfect teachings of Buddha can
be called the Sangha. 

They should observe these teachings and train their minds accordingly.
Thus, the Buddha’s Sangha will theoretically include everyone, but, in fact
only those who have the same religious faith are members. 

(Nirvana Sutra)