you must have a doctrine

In his epistle to the Romans, Paul mentions predestination in close proximity to God's foreknowledge: "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) Christians who seek to be biblical in their thinking must have a doctrine of election and of predestination. These concepts were not invented by Augustine in his debate with Pelagius, or by Luther in his debate with Erasmus, or by Calvin in his debate with Pigius, or by Edwards in his debate with Chubb. These concepts of election and predestination are found in the text of Scripture. If you really want to be biblical as a Christian, it is incumbent upon you to hold to the biblical doctrine of predestination and of election and not some other construction. 

R. C. Sproul, St. Andrews Expositional Commentary on 1 - 2 Peter