Christ does not say that man will not or shall not serve two masters, but that he cannot. The interests of God and the interests of mammon have no union or sympathy. Just where the conscience of the Christian warns him to forbear, to deny himself, to stop, just there the worldling steps over the line, to indulge his selfish propensities. On one side of the line is the self-denying follower of Christ; on the other side is the self-indulgent world lover, pandering to fashion, engaging in frivolity, and pampering himself in forbidden pleasure. On that side of the line the Christian cannot go. MB 93.2
No one can occupy a neutral position; there is no middle class, who neither love God nor serve the enemy of righteousness. Christ is to live in His human agents and work through their faculties and act through their capabilities. Their will must be submitted to His will; they must act with His Spirit. Then it is no more they that live, but Christ that lives in them. He who does not give himself wholly to God is under the control of another power, listening to another voice, whose suggestions are of an entirely different character. Half-and-half service places the human agent on the side of the enemy as a successful ally of the hosts of darkness. When men who claim to be soldiers of Christ engage with the confederacy of Satan, and help along his side, they prove themselves enemies of Christ. They betray sacred trusts. They form a link between Satan and the true soldiers, so that through these agencies the enemy is constantly working to steal away the hearts of Christ's soldiers. MB 94.1
The strongest bulwark of vice in our world is not the iniquitous life of the abandoned sinner or the degraded outcast; it is that life which otherwise appears virtuous, honorable, and noble, but in which one sin is fostered, one vice indulged. To the soul that is struggling in secret against some giant temptation, trembling upon the very verge of the precipice, such an example is one of the most powerful enticements to sin. He who, endowed with high conceptions of life and truth and honor, does yet willfully transgress one precept of God's holy law, has perverted His noble gifts into a lure to sin. Genius, talent, sympathy, even generous and kindly deeds, may become decoys of Satan to entice other souls over the precipice of ruin for this life and the life to come. MB 94.2
“Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world.” 1 John 2:15, 16. MB 95.1