And I will put My spirit within you… – Ezekiel 36:27

Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you… – 2 Corinthians 6:17

Men by nature are of another spirit from that of God, and they are under subjection to that evil spirit, the Prince of the power of the air. When the Lord comes to gather out His own, fetching them out from among the heathen, He effects the separation by doing according to this word, “I will put My spirit within you.” This done, the individual becomes a new man. Those who have the Spirit are not of the world, nor like the world; and they soon have to come out from among the ungodly, and to be separate; for difference of nature creates conflict. God’s Spirit will not dwell with the evil spirit: you cannot have fellowship with Christ and with Belial; with the kingdom of heaven and with this world. I wish that the people of God would again wake up to the truth that to gather out a people from among men is the great purpose of the present dispensation. It is still true, as James said at the Jerusalem Council, “Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for His name.” We are not to remain clinging to the old wreck with the expectation that we shall pump the water out of her and get her safe into port. No; the cry is very different-“Take to the lifeboat! Take to the lifeboat!” You are to quit the wreck, and then you are to carry away from the sinking mass that which God will save. You must be separate from the old wreck, lest it suck you down to sure destruction. Your only hope of doing good to the world is by yourselves being “not of the world,” even as Christ was not of the world. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/2200.cfm