And we know that we are of God, and the whole world lieth in wickedness. – 1 John 5:19

Those who are sanctified have ceased to be unequally yoked together with unbelievers; they have ceased to run with the multitude to do evil; they are not conformed to this present evil world; they are strangers and pilgrims upon the earth. The more assuredly this is true of them the better. There are some, in these apostate days, who think that the church cannot do better than to come down to the world to learn her ways, follow her maxims, and acquire her “culture.” In fact, the notion is that the world is to be conquered by our conforming to it. This is as contrary to Scripture as the light is to the darkness. The more distinct the line between him that feareth God and him that feareth him not, the better all round. It will be a black day when the sun itself is turned into darkness. When the salt has lost its savor, and no longer opposes putrefaction, the world will rot with a vengeance. That text is still true, “Ye are of God, little children, and the whole world lieth in the wicked one.” The seed of the woman knows no terms with the serpent brood but continual war. Our Lord saith that in this matter He came not to send peace on the earth, but a sword. “Because ye are not of the world, but I have chosen you out of the world, therefore the world hateth you.” If the church seeks to cultivate the friendship of the world, she has this message from the Holy Ghost by the pen of the apostle James: “Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God? whosoever therefore will be a friend of the world is the enemy of God.” He charges all who would please the world with the black and filthy crime of spiritual adultery. The heart which ought to be given to Christ and purity must not wander forth wantonly to woo the defiled and polluted things of this present evil world. Separation from the world is Christ’s prayer for us. “Sanctify them through Thy truth: Thy word is truth.” -John 17:17 ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1890.cfm