I pulled a book off the shelf that we've had
for probably over 20 years yet I've never read.
It is Christianity & Liberalism by J. Gresham
Machen.

I can't give a full review here because I am
only on page 8, but I was captivated from the
first paragraph of the introduction.

"Light may seem at times to be an impertinent
intruder, but it is always beneficial in the
end. The type of religion which rejoices in
the pious sound of traditional phrases,
regardless of their meanings, or shrinks from
"controversial" matters, will never stand amid
the shocks of life. In the sphere of religion,
as in other spheres, the things about which men
are agreed are apt to be the things that are
least worth holding; the really important things
are the things about which men will fight."

Already I have used my underlining pen a lot.
Expect to read more about Machen's book in the future.