Same thing as saying I don't believe in the Bible, since predestination is quite explicitly a part of it.
29 For whom He foreknew, He also predestined to be conformed to the image of His Son, that He might be the firstborn among many brethren. (Romans 8:29)
30 Moreover whom He predestined, these He also called; whom He called, these He also justified; and whom He justified, these He also glorified. (Romans 8:30)
5 having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will, (Ephesians 1:5)
11 In Him also we have obtained an inheritance, being predestined according to the purpose of Him who works all things according to the counsel of His will, (Ephesians 1:11)