This is a very historically important letter from C. H. Spurgeon to his "friends." It is perhaps the Trustees of the Tabernacle or similar. It is clearly a group close to him and to the Tabernacle as he includes them as sources of encouragement in the same sentence as his brother. 

This letter was written by Spurgeon shortly after submitting his letter of withdrawal from the Baptist Union over the Downgrade Controversy. Spurgeon took his stand against modernism, liberalism, and compromise of Scripture and the Atonement. But it cost him emotionally and in health. His discouragement is evident here.

The Downgrade Controversy among the Baptists flared in 1887 with Spurgeon's first "Down-grade" article, published in The Sword & the Trowel. In the ensuing "Downgrade Controversy," the Metropolitan Tabernacle disaffiliated from the Baptist Union, making Spurgeon's congregation as the world's largest independent church. Spurgeon framed the controversy in this way:

Believers in Christ's atonement are now in declared union with those who make light of it; believers in Holy Scripture are in confederacy with those who deny plenary inspiration; those who hold evangelical doctrine are in open alliance with those who call the fall a fable, who deny the personality of the Holy Ghost, who call justification by faith immoral, and hold that there is another probation after death... It is our solemn conviction that there should be no pretence of fellowship. Fellowship with known and vital error is participation in sin.

The Controversy took its name from Spurgeon's use of the term "Downgrade" to describe certain other Baptists' outlook toward the Bible (i.e., they had "downgraded" the Bible and the principle of sola scriptura). Spurgeon alleged that an incremental creeping of the Graf-Wellhausen hypothesis, Darwin's theory of evolution, and other concepts were weakening the Baptist Union. Spurgeon emphatically decried the doctrine that resulted:

Assuredly the New Theology can do no good towards God or man; it, has no adaptation for it. If it were preached for a thousand years by all the most earnest men of the school, it would never renew a soul, nor overcome pride in a single human heart.

Interestingly, the "dry rot" metaphor here he also quotes in an article in the Sword & Trowel in a discussion about the Downgrade. There he attributes it to a fellow Baptist friend.

"Dear Friends,

As your kind gift is left to me, I have paid it in to the funds of the Tabernacle itself, for my illness has involved many expenses, & our funds are much tried. I need more help.

The tender love of yourself & brother always cheers me much. I have had storm after storm of late. Still, the barque will not sink. The Downgrade controversy tried me much, & most of all the dodge by which it was burked. The Dry Rot is among the Baptists much more than I ever imagined.

The Lord of Hosts is with us.

I can barely stand, & cannot walk, but I am pretty right all but the legs. Mrs. S. remains very sadly.

Yours gratefully,
C. H. Spurgeon"

Very clean and bright. Light folds. Complete.