“Come Now, Let Us Reason Together”

A Holy God Invites a Sinful People to Return
Isaiah 1:1–20

For the next few months at GPC Kikuyu, we are sitting under the ministry of what has often been called “the Fifth Gospel” “the Evangelical Prophet” or “The Romans of The Old Testament” Written some seven centuries before Christ, Isaiah is relentless in its clarity about God’s covenant love, His sovereign rule over the nations, and His uncompromising holiness. Refrains echo again and again: “The Holy One of Israel,” “Behold,” “In that day,” “The mouth of the LORD has spoken.”

Isaiah lived and ministered through the reigns of four kings of Judah—Uzziah, Jotham, Ahaz, and Hezekiah. And he leaves us in no doubt: these are not his opinions. He is conveying the very words of God to a privileged, covenant people who had wandered far from home.

Isaiah 1 opens in a courtroom. Heaven and earth are summoned as witnesses. God Himself steps forward—not only as Judge, but also as Prosecutor, and even more strikingly, as a wounded Father.

“Children have I reared and brought up, but they have rebelled against me.” (Isaiah 1:2)

This is relational grief. The ox knows its owner. The donkey knows its master’s crib. But God’s own people—redeemed, blessed, settled, and sustained—do not know Him. They do not understand.

1. A Holy Father Confronts Rebellion (vv. 2–9)

Isaiah piles on the language:
A sinful nation. Laden with iniquity. Offspring of evildoers. Children who deal corruptly.

Here were covenant people living as though God were irrelevant. The prophet then takes us into a kind of divine triage room. The diagnosis is grim – The whole head is sick. The heart is faint. The body is covered in untreated wounds—bruised, raw, infected. This is not a sudden accident but long-term neglect. A slow moral and spiritual collapse. And the consequences are visible: desolation, invasion, fragility. A nation reduced to a lonely hut in a cucumber field.

2. A Holy God Rejects Empty Religion (vv. 10–17)

If rebellion were the only problem, it would be bad enough. But Isaiah exposes something even more dangerous: religion without repentance. God compares His people to Sodom and Gomorrah—not because they had abandoned worship, but because they had hollowed it out. Sacrifices continued. Festivals remained full. Prayers multiplied. But then our father says: “I cannot endure… I hate… I am weary.”

Why? “Your hands are full of blood.”

Worship divorced from obedience is not neutral—it is offensive. God is not impressed by noise, numbers, or novelty. He is seeking changed lives.

So the call comes, sharp and practical:

Wash yourselves.
Remove evil.
Learn to do good.
Seek justice.
Correct oppression.
Care for the vulnerable.

Repentance, Isaiah insists, is active. It moves. It bears fruit. We are not saved by good works—but we are certainly not saved without them. It is possible to be in the gathering of the saved and yet remain unsaved. Hypocrisy is not merely a moral failure; it is a spiritual danger.

3. A Gracious God Invites Repentant Sinners (vv. 18–20)

After all the charges, all the exposure, all the truth-telling, the Judge returns to the bench and says: “Come now, let us reason together, says the LORD…”

These may be among the most breathtaking words in the Old Testament.

God does not say, “Get out.” He says, “Come.” He does not say, “Explain yourself.” He says, “Let us reason together.”

And yet—cleansing is promised. This is not negotiation between equals. It is mercy offered by a holy God to guilty people. Two paths are then set before His people: If they are…

• Willing obedience  – they will enjoy life and blessing.
• Stubborn rebellion – they will suffer judgment and loss

Isaiah 1 leaves us with a single, pressing question – God has spoken, He has exposed and He has invited. You and I have heard the charge. We have seen the stain and the ugliness of sin.
We have been offered cleansing. Will you come?