Let the wicked forsake his way, and the unrighteous man his thoughts: and let him return unto the LORD, and He will have mercy upon him; and to our God, for He will abundantly pardon. – Isaiah 55:7

“What is the gospel?” Well, the gospel, as I take it, can be looked at in various ways, but I will put it as this-the gospel is the preaching of a full, free, present, everlasting pardon to sinners through Jesus Christ’s atoning blood. If I understand the gospel at all, it has in it a great deal more than this; but still this is the substance of it. I have to preach the great fact that while all have sinned, Christ hath died, and to all penitents who now confess their sins and put their trust in Christ, there is a full, free pardon-free in this respect, that you have nothing to do in order to get it. The meanest sin-stricken sinner has simply to pour out his plaintive griefs before God; that is all He asks.

There is no need to pass through years of penance, of hard labor, and of trial; the gospel is as free as the air you breathe. You do not pay for breathing; you do not pay for seeing the sunlight, nor for the water that flows in the river as you stoop to drink it in your thirst. So the gospel is free; nothing is to be done in order to get it. No merits need be brought in order to obtain it. There is free pardon for the chief of sinners through Jesus Christ’s blood… If now, sinner, God hath put it in thine heart to seek Him, the pardon which He is prepared to give thee, is a full one; not a pardon for a part of your sins, but for all at once.

“Here’s pardon for transgressions past,
It matters not how black they’re cast,
And, oh! my soul with wonder view,
For sins to come here’s pardon too.”

~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0199.cfm