TULIP, also known as the five points of Calvinism, consists of five doctrines that summarize Calvinism, or the doctrines of predestination and election. These five points are a response to the Five Articles of Remonstrance, which were five points that were raised in objection to Calvinism.
For a full list of answers to objections against the five points of Calvinism, see Answers to Objections Against Calvinism