"I HAVE taken two texts from two successive chapters of the book of Joshua.
The first is from Joshua the seventh, at the third verse.
The spies 
who were sent to Ai returned to Joshua and said to him, "Let
not all the people go up; but let about two or three thousand men go up
and smite Ai."
This policy led to a disastrous defeat and our other text
gives us the Lord's command concerning the new attack.
You will find it
in the eighth of Joshua and the first verse—"The
Lord said unto Joshua, Fear not, neither be dismayed: take all the
people of war with you, and arise, go up to Ai; see, I have given into
your hand the king of Ai, and his people, and his city, and his land."
***The
two texts may be condensed into—first, the advice of the spies, to
employ only a part of the people in the assault upon Ai—"Let not all the
people go up." And, secondly, the command of God to let every fighting
man go forth to the war—"Take all the people of war with you."
Brethren,
like Israel, we are called to war and we have a greater than Joshua at
our head, in whose name we conquer!
I. Let us consider THE ADVICE OF THE SPIES which led
to such a shameful defeat.
And here we shall have to deal with the error
of supposing that 
only a part of the Church will be sufficient to
perform the work of the whole—that a large proportion may be idle—and
that the rest will be quite enough to fight the Lord's battles. I feel
it to be an error which, though not perhaps theoretically held by any of
us, is practically to be seen abroad in our Churches and needs to be
met and put to an end.
In Joshua's day this
error sprang up among the Israelites because, on account of their sins,
God was displeased with them. The commencement of the chapter tells us
that the Lord God was angry because the children of Israel had committed
a trespass in the accursed thing. Because of the sin of Achan, the
anger of the Lord was kindled against the people. That was the real
reason of their defeat before Ai, but out of that secret cause grew the
more manifest source of defeat—because God was displeased with them,
they were left to themselves and, therefore, they adopted a fatal
policy.
II. In the second place, my text contains THE COMMAND THAT ALL ISRAEL
SHOULD GO FORTH TO THE FIGHT. "Take all the men of war with you."
I will
mainly address myself to my Brothers in Christ and what I 
have to say
to them I say humbly, speaking mainly to myself. Brothers, we must have
all our Church members go to the war. The baggage of our army is too heavy.
The camp followers are too many. We need to turn out the drones and we
need an increase of true working bees.
Q: How is it to be done?
A: We must be,
ourselves, deeply impressed with the evil brought upon idle Christians
by their idleness and the evil which they bring upon the rest of the
Church."
Charles Spurgeon