No one can serve two masters, for either he will hate the one and love the other, or he will be devoted to the one and despise the other. You cannot serve God and money. (Matthew 6:24)
Jesus is an all-or-nothing proposition. This is because He is all. He is the all in all (Colossians 3:11). He is everything good, He is sufficient. Nothing should compete with Him. Hence the warning about two masters.
Barnes’ Notes on the Bible
No man can serve two masters … – Christ proceeds to illustrate the necessity of laying up treasures in heaven from a well-known fact, that a servant cannot serve two masters at the same time. His affections and obedience would be divided, and he would fail altogether in his duty to one or the other. One he would love, the other he would hate. To the interests of the one he would adhere, the interests of the other he would neglect. This is a law of human nature. The supreme affections can be fixed on only one object.
Please be aware of any growing idols in your (and my) life, whom you (and I) are serving. We cannot have two masters else we will hate the one. Jesus is too precious to risk hating Him, even if for a short while before realizing and then repenting.
Answer to the Title’s question: We will hate Jesus when we serve another master.