Exodus 20:25 (a devotion by C.H. Spurgeon)
"If thou lift up thy tool upon it, thou hast polluted it." — Exodus 20:25

God's altar was to be built of unhewn stones, that no trace of human skill or labour might be seen upon it. Human wisdom delights to trim and arrange the doctrines of the cross into a system more artificial and more congenial with the depraved tastes of fallen nature; instead, however, of improving the gospel carnal wisdom pollutes it, until it becomes another gospel, and not the truth of God at all. All alterations and amendments of the Lord's own Word are defilements and pollutions. The proud heart of man is very anxious to have a hand in the justification of the soul before God; preparations for Christ are dreamed of, humblings and repentings are trusted in, good works are cried up, natural ability is much vaunted, and by all means the attempt is made to lift up human tools upon the divine altar. It were well if sinners would remember that so far from perfecting the Saviour's work, their carnal confidences only pollute and dishonour it. The Lord alone must be exalted in the work of atonement, and not a single mark of man's chisel or hammer will be endured. There is an inherent blasphemy in seeking to add to what Christ Jesus in His dying moments declared to be finished, or to improve that in which the Lord Jehovah finds perfect satisfaction. Trembling sinner, away with thy tools, and fall upon thy knees in humble supplication; and accept the Lord Jesus to be the altar of thine atonement, and rest in Him alone.

Many professors may take warning from this morning's text as to the doctrines which they believe. There is among Christians far too much inclination to square and reconcile the truths of revelation; this is a form of irreverence and unbelief, let us strive against it, and receive truth as we find it; rejoicing that the doctrines of the Word are unhewn stones, and so are all the more fit to build an altar for the Lord.