The phrase "set apart the Lord Christ ... as holy" means to acknowledge Christ's holiness. This action is referred to as if it were putting something in a place of honor. (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here a person's inner being and center of emotions is referred to as the "heart." AT: "with all your will" (See: [[rc://en/ta/man/translate/figs-metaphor]])