George Mueller emphasizes the importance of being a committed Christian from the very beginning of one's spiritual journey, urging believers to live distinctly for God and bear fruit for His glory. He encourages young Christians to strive for holiness and happiness, making it evident to the world that they belong to the kingdom of heaven. Mueller stresses that while one can glorify God in their earthly business, they must be willing to give up anything contrary to God's will. He acknowledges that all believers are prone to sin and must continually seek forgiveness through Jesus Christ. Ultimately, he calls for a life that reflects Christ, leading to increased joy and usefulness in God's service.

So, my beloved younger brethren and sisters in Christ at the very outset of your spiritual life, say boldly, “I will be, by the grace of God, an out-and-out Christian, living for God. I will, by His grace, seek to bear fruit to His glory and honour. I will, by His grace, seek to have done with this sinful world. I will, by His grace, strive so to live, that a line of demarcation shall be clearly seen between me and the world, and that the people of the world shall seek to have no intercourse with me, seeing that I do not belong to them, but that I belong to the kingdom of heaven.” That is what we have to aim after; and what would be the result? Not only should we be holy men and women, but also happy men and women, in whom God delights; and we should also be useful men and women. The world ought to say of each of us, “If ever there was a Christian, it is surely that man or that woman.” “Surely that man or woman has been with Jesus.” If the world does not say that of us, there is something wanting. We ought to be ashamed, if any one is able to live three or four days in the house with us, without finding out that we are not of the world, but are born again. And that is not the only use of thus bearing testimony; it will also be very helpful to our brethren in the Lord. Let me insist particularly, my beloved brethren and sisters, but especially you, my younger brethren and sisters, on this point—that of being out-and-out for God in the very outset. We must be opposed to the world, and the flesh, and entirely for Christ. This is the purpose for which we are left in the world. I do not say we are to give up our ordinary business. I have seen much of this; there is often too much readiness in giving up the earthly business, and it is often done hastily. I have found that men may greatly glorify God in their earthly business, and I do not say that they are to forsake that business in order to become evangelists, missionaries. district visitors, tract distributors, or the like. We may serve and honour Him well whilst occupied with the business of this life. If God does call us, by all means go at once; but do not go unless He calls. We require a special call from God, and even when we think we have received it, let us make it a matter of consideration. Let us prayerfully, quietly, and calmly look to God before taking such a step. But, again, I say, if there be anything, whatever it may be, and however dear it may be, which is contrary to the divine will, let us give it up at once, and aim after being out-and-out, and decided for God in every way. The result will be increased happiness, joy, and holiness; and our usefulness will increase more and more. ​ In connection with this, I would especially state that, though we all ought to aim after conformity to the mind of Christ, yet we all more or less fail. It is deeply important to mark, that all of us are liable to sin, and do sin. If any man come to me, and say, “I do not sin,” I would say, “My brother, you are mistaken; perhaps you do not know what sin is, or you do not know your own state.” All of us, though not living in sin, are yet liable to sin; if not in acts, yet in words; or if not even in words, yet in feelings or desires. We are all apt to fall short of what we might be and of what we ought to be. What then? Well, we must make confession, and come afresh to the blood of Jesus Christ, and have these sins washed away. - George Muller