Open theism, also known as openness theology and free will theism, is a theological movement that has developed within Christianity as a rejection of the synthesis of Greek philosophy and Christian theology. Open theism arises out of the free will theistic tradition of the church, which goes back to the early church fathers. Open theism is typically advanced as a biblically motivated and logically consistent theology of human and divine freedom (in the libertarian sense), with an emphasis on what this means for the content of God's foreknowledge and exercise of God's power. Open theist theologian Thomas Jay Oord identifies four paths to open and relational theology: following the biblical witness, following themes in some Christian theological traditions, following the philosophy of free will, and following the path of reconciling faith and science. Roger E. Olson said that open theism triggered the "most significant controversy about the doctrine of God in evangelical thought" in the late 20th and early 21st centuries. In short, open theism posits that since God and humans are free, God's knowledge is dynamic and God's providence flexible. Whereas several versions of traditional theism picture God's knowledge of the future as a singular, fixed trajectory, open theism sees it as a plurality of branching possibilities, with some possibilities becoming settled as time moves forward. Thus, the future, as well as God's knowledge of it, is open (hence, "open" theism). Other versions of classical theism hold that God fully determines the future, entailing that there is no free choice (the future is closed). Yet other versions of classical theism hold that, though there is freedom of choice, God's omniscience necessitates God's foreknowing what free choices are made (God's foreknowledge is closed). Open theists hold that these versions of classical theism do not agree with the biblical concept of God; the biblical understanding of divine and creaturely freedom; and/or result in incoherence.