The sanctification set forth in the Scriptures embraces the entire being—spirit, soul, and body. Paul prayed for the Thessalonians that their “whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ” (1 Thessalonians 5:23). Again he writes to believers: “I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God” (Romans 12:1). In the time of ancient Israel every offering brought as a sacrifice to God was carefully examined. If any defect was discovered in the animal presented, it was refused; for God had commanded that the offering be “without blemish.” So Christians are bidden to present their bodies, “a living sacrifice, holy, acceptable unto God.” In order to do this, all their powers must be preserved in the best possible condition. Every practice that weakens physical or mental strength unfits man for the service of his Creator.
And will God be pleased with anything less than the best we can offer? Said Christ: “Thou shalt love the Lord thy God with all thy heart.” Those who do love God with all the heart will desire to give Him the best service of their life, and they will be constantly seeking to bring every power of their being into harmony with the laws that will promote their ability to do His will.... . NL 17-NL 18.1

The world is given up to self-indulgence. “The lust of the flesh, and the lust of the eyes, and the pride of life” control the masses of the people. But Christ's followers have a holier calling....
To those who comply with the conditions, “Come out from among them, and be ye separate, ... and touch not the unclean,” God's promise is, “I will receive you, and will be a Father unto you, and ye shall be My sons and daughters, saith the Lord Almighty” (2 Corinthians 6:17, 18). It is the privilege and the duty of every Christian to have a rich and abundant experience in the things of God.... The bright beams of the Sun of Righteousness shine upon the servants of God, and they are to reflect His rays. As the stars tell us that there is a great light in heaven with whose glory they are made bright, so Christians are to make it manifest that there is a God on the throne of the universe whose character is worthy of praise and imitation. The graces of His Spirit, the purity and holiness of His character, will be manifest in His witnesses.... . NL 18.2-NL 18.3