The following are some excerpts from the book "The Cross" by Martyn Lloyd-Jones. These are from the first chapter. One of the clearest gospel messages I've ever read.
"God, unlike us, is light, and in him is no darkness at all. God is just, God is holy. God is righteous. Of course, that means nothing to us. How can we think of holiness? We, ugly, foul, vile, sinful creatures. No, we do not understand the righteousness of God. But God is righteous, he is the law giver, he is holy, he is of so pure a countenance that he cannot even look upon sin; and God cannot pretend that he has not seen it. God sees sin. He sees everything. He must punish sin. His own holy nature insists upon it and he has told us abundantly that he is going to do so. So here is the problem. Man is a guilty sinner, God is a holy God.
I know the most important thing about every single one of you, and that is that each of you is a vile sinner. I don't care who you are, because all have sinned and come short of the glory of God. I do not care what particular form your sin takes. I do not care what your sins are. But what I have authority to tell you is this. Though you may be the vilest man or woman ever known, and though you may until this moment have lived your life in the gutters and brothels of sin in every shape and form, I say this to you: be it known unto you that through this man, this Lord Jesus Christ, is preached unto you the forgiveness of sin. And by him all who believe, you included, are at this moment justified entirely and completely from everything you have ever done - if you believe that this is the Lord Jesus Christ, the Son of God, and that he died there on the cross, for your sins and to bear your punishment. If you believe that, and thank him for it, and rely utterly only upon him and what he has done, I tell you, in the name of God, all your sins are blotted out completely, as if you had never sinned in your life, and his righteousness is put on you and God sees you perfect in his Son. That is the message of the cross, that is Christian preaching, that it is our Lord who saves us, by dying on the cross, and that nothing else can save us, but that that can save whosoever believes in him."
You can listen to the late Martyn Lloyd-Jones here. This is a radio ministry that has remastered 1600 of his sermons and broadcasts them weekly with a free archive.