The trouble I find with psychology is that it is simply an attempt to give you quiet nerves instead of giving you a quiet heart. I want to be fair to psychology. It can give us, up to a point, quiet nerves, but that is not what we need—we need a quiet heart. Thank God for something that, as far as it goes, can give us quiet nerves, but do you want to be at rest on the surface or do you want to be at rest in the very depths and vitals of your being? It is at that point that the gospel claims that it, and it alone, can meet and satisfy our deepest need, and here in John 14 we are told exactly how it does that. . . .
What seems to me to be so entirely different about the gospel, at the very beginning, is that it always faces facts, it is always realistic, it never conceals anything. Read these chapters of John’s Gospel, and you will find that our Lord brought these men face-to-face with the very worst, whereas all the other teachings and philosophies try to hide the worst from us. My heart will not be really quiet until I have been told the very worst and faced it, and then I can surmount it. I do not believe in a teaching that simply plays tricks with me. I have no use for a philosophy that tells me there is no such thing as matter, and because of that there can be no pain, and therefore I do not have pain—when I know there is pain. I know that may work psychologically; it may convince me for a time—I believe the lie and am relieved. But I do not merely want to be relieved of my pain. I want the disease to be faced and tackled.
Martyn Lloyd-Jones, Let Not Your Heart Be Troubled (Kindle Edition)