J.C. Ryle on the difference between fake faith with true faith:
...That man must be blind who does not see thousands around him who are daily preferring the world to God--placing the things of time before the things of eternity, and the things of the body before the things of the soul. We may not like to admit this, and we try hard to blink the fact. But so it is.
And why do they do so? No doubt they will all give us reasons and excuses. Some will talk of the snares of the world--some of the want of time--some of the peculiar difficulties of their position--some of the cares and anxieties of life, some of the strength of temptation--some of the power of passions--some of the effects of bad companions. But what does it come to after all? There is a far shorter way to account for the state of their souls--they do not believe. One simple sentence, like Aaron's rod, will swallow up all their excuses--they have no faith.
They do not really think what God says is true. They secretly flatter themselves with the notion, "It will surely not be fulfilled--there must surely be some other way to heaven beside that which ministers speak of--there cannot surely be so much danger of being lost." In short, they do not put implicit confidence in the words that God has written and spoken, and so do not act upon them. They do not thoroughly believe hell, and so do not flee from it--nor heaven, and so do not seek it--nor the guilt of sin, and so do not turn from it--nor the holiness of God, and so do not fear Him--nor their need of Christ, and so do not trust in Him, nor love Him. They do not feel confidence in God, and so venture nothing for Him. Like the boy Passion, in Pilgrim's Progress, they must have their good things now. They do not trust God, and so they cannot wait.
Now how is it with ourselves? Do we believe all the Bible? Let us ask ourselves that question. Depend on it, it is a much greater thing to believe all the Bible than many suppose. Happy is the man who can lay his hand on his heart and say, "I am a believer."
We talk of infidels sometimes as if they were the rarest people in the world. And I grant that open avowed infidelity is happily not very common now. But there is a vast amount of practical infidelity around us, for all that, which is as dangerous in the end as the principles of Voltaire and Paine. There are many who Sunday after Sunday repeat the creed, and make a point of declaring their belief in all that the Apostolic and Nicene forms contain. And yet these very persons will live all the week as if Christ had never died, and as if there were no judgment, and no resurrection of the dead, and no life everlasting at all. There are many who will say, "Oh, we know it all," when spoken to about eternal things and the value of their souls. And yet their lives show plainly they know not anything as they ought to know; and the saddest part of their state is that they think they do!
It is an awful truth, and worthy of all consideration, that knowledge not acted upon, in God's sight, is not merely useless and unprofitable. It is much worse than that. It will add to our condemnation and increase our guilt in the judgment day. A faith that does not influence a man's practice is not worthy of the name. There are only two classes in the Church of Christ--those who believe and those who do not. The difference between the true Christian and the mere outward professor just lies in one word--the true Christian is like Moses, "He has faith"; the mere outward professor has none. The true Christian believes, and therefore lives as he does; the mere professor does not believe, and therefore is what he is. Oh, where is our faith? Let us not be faithless, but believing.
Ryle, J.C. Holiness: Its Nature, Hindrances, Difficulties, and Roots. Chapter VIII: Moses, an Example. pg. 125-126.