What wonderful, freeing, life-giving words these are! God does not justify the godly, or declare that the good are righteous, but rather, the ungodly. Through faith we are not made good (though that happens over time, sure enough) but rather we are declared -- by virtue of Christ's precious blood -- to be righteous. Now and always. This I believe is an unchanging foundation for the believer to stand upon in his approach to God. It is also an unending fountain of joy for the Christian.
Martyn Lloyd-Jones makes this truth very practical...
To make it quite practical I have a very simple test. After I have explained the way of Christ to somebody I say “Now, are you ready to say that you are a Christian?” And they hesitate. And then I say, “What’s the matter? Why are you hesitating?” And so often people say, “I don’t feel like I’m good enough yet. I don’t think I’m ready to say I’m a Christian now.”
And at once I know that I have been wasting my breath. They are still thinking in terms of themselves. They have to do it. It sounds very modest to say, “Well, I don’t think I’m good enough,” but it’s a very denial of the faith. The very essence of the Christian faith is to say that He is good enough and I am in Him. As long as you go on thinking about yourself like that and saying, “I’m not good enough; Oh, I’m not good enough,” you are denying God – you are denying the gospel – you are denying the very essence of the faith and you will never be happy. You think you’re better at times and then again you will find you are not as good at other times than you thought you were. You will be up and down forever.
How can I put it plainly? It doesn't matter if you have almost entered into the depths of hell. It does not matter if you are guilty of murder as well as every other vile sin. It does not matter from the standpoint of being justified before God at all. You are no more hopeless than the most moral and respectable person in the world.
― D. Martyn Lloyd-Jones, Spiritual Depression