Calvinism
Piper's theology is Reformed[15] and Baptist.[16] He also believes in double predestination, which includes "unconditional reprobation" as a corollary to the Calvinistic doctrine of unconditional election, and he subscribes to the Leibnizian view that God runs the universe in such a way that it will be the best of all possible universes.[17] Piper believes in justification by faith alone apart from works,[18] and his teachings emphasize the need for the active perseverance of the believer in faith, sanctification, and enduring sufferings, as this is evidence of God's saving grace. A once-professing Christian who does not persevere in faith to the end demonstrates that he was never a true believer in the first place.[19][20]
Eschatology
Piper describes himself as an "optimistic premillennialist"[21] and holds a post tribulation view of the second coming of Jesus.[22][23] He maintains that Romans 11 teaches that a mass in-gathering of ethnic Israel will be saved when the hardening of their hearts is removed at Jesus' second coming.[24] He advocates the importance of hoping in the resurrection of the dead at Christ's return.[25]
Law and covenant
Piper does not don any of the typical hermetical frameworks, but claims he is furthest from dispensationalism, and closest to covenant theologian, or a New Covenant theologian in matters of the Law and covenants, but agrees with the Dispensationalist that there will be a millennium.[26] He says that the Law was meant by God to reveal sin and show man's inability to live up to God's righteous standards[27]. Christians, living under the new covenant, are not under the old-covenant law but able to fulfill its intent through faith in Jesus Christ.[28][29] Piper teaches that God has only one covenant people, mostly believing Jews in the Old Testament, and now that relationship has been superseded by the church.[30] Thus, the Church is rightful inheritor of all the promises made to ethnic Israel (land, kingdom, etc.), and Jews who reject Jesus as Messiah have no divine right of claim on those promises.[31]
Spiritual gifts
Regarding spiritual gifts, Piper is a continuationist.[32] That is, he believes that supernatural gifts such as prophecy, miracles, healings, and speaking in tongues have not ceased and should be sought by the church,[33] in particular with regard to missions and evangelism. He does believe, however, that the office of apostle has ceased [34] and that the gift of prophecy in the church is not the same as the inspiration of scripture [35]. While he believes that God's supernatural revelation in the N.T. gift of prophecy is without error, he says that the prophet's perception, understanding and delivery of that revelation is imperfect and fallible [36], thus N.T. prophecies are subject to sifting[37].
Gender roles
Piper holds to a complementarian view of gender roles,[38] and was co-editor of Recovering Biblical Manhood and Womanhood with Wayne Grudem. One of the chapters has been reprinted several times as an independent short book called What's the Difference?.
http://www.svchapel.org/resources/book-reviews/4-christian-living/127-future-grace-by-john-piper
please read the book review by Gary Gilley of “Future Grace”, Piper’s book. My church did that book in Sunday school and it was awful.
Piper has a Roman view of grace - he denies that grace is primarily God’s unmerited favor, and he opposes a believer having gratitude for God’s provisions. This, he says, is a “debtor’s ethic”. Although Piper is a useful devotional speaker (he was formally trained in poetry), he is a doctrinally tangled individual.