What does Reverend Parris' trying to say in the below quote from The Crucible?"There is either obedience or the church will burn like Hell is...

Much about Parris' character is revealed in the quote
featured.  The idea of a world where only binary oppositions exist is something that
lies at the root of Parris' character.  Either there is complete love for Parris or he
is convinced that his "flock" is driving to subvert him.  Either someone is in total
accord with each and every single thing that he does or he is convinced that the
individual is a witch and an agent of Satan.  Either Parris is in total control or he
views himself as being discarded.  Parris sees the world in strict binary oppositions,
like much of Salem.  There is no complexity, no nuanced state of being, and
consciousness is not intricate.  This is why the fundamental idea in the quote is
relevant to Parris.  Either Parris will have total devotion from his followers, or
obedience, or he believes that the church will suffer.  In this, Parris draws a
distinct, a line in the sand, where he either gets total submission from members of the
community or those who dissent are cast into hell.

To a
large extent, Parris' statement is a direct attack on Proctor.  This is why Proctor's
line in response is whether or not Parris can actually stop talking about Hell and
damnation.  Parris' quote is meant to silence expression and dissent and "fall in line"
with the church's demands.  Proctor has represented an opposite approach to this in that
he is not an advocate of the organized religion of the church because he is not an
advocate of Parris.  In this, Parris recognizes Proctor to be a threat and develops the
argument that in its most base form is "Either you are with me or against me."  Parris
figures that motivation by fear is the best way to ensure allegiance and loyalty. 
Proctor does not see reality in such a mnner.

In the end,
Parris quote is meant to convey the sense of fear of "the other" that gripped Salem. 
Miller is wise enough to make the argument that Parris and those in the position of
power helped to create this fear, one that after being properly stoked, such individuals
could simply say that they are "following the will of the people."  Statements like
Parris in which individuals remain silent and follow church orders or are condemned to
Hell is a reflection of such a condition in Salem.