Cottrell returned to Cincinnati Christian University in 1967 holding a conservative view of the Bible and Christianity. He has since authored over 20 books on Christian theology and doctrine. Frequent topics include grace, faith, baptism, Biblical accuracy, Biblical consistency, and the nature of God. He has also tackled other issues including leadership and gender roles in Christianity. Cottrell has additionally authored several Biblical commentaries. His books include Baptism: A Biblical Study, The Faith Once for All: Bible Doctrine for Today, Bible Prophecy and End Times, Set Free! What the Bible Says About Grace, Tough Questions, Biblical Answers Parts One and Two, 13 Lessons on Grace and His Truth: Scriptural Truths About Basic Doctrines. He has also authored several Biblical commentaries.
Theology
Cottrell supports conservative beliefs of inerrancy and infallibility of the Bible and that baptism by immersion is the Biblical method. Cottrell is critical of Calvinism and has mostly supported Arminianism.
Trinity
Dr. Cottrell believes that the "Father, Son and Spirit are distinct persons who exist simultaneously and interact with one another." He rejects a false view of the Trinity called modalism which says that there are no distinctions between God the Father, God the Son, and God the Holy Spirit. Dr. Cottrell calls modalism heretical and a "seriously false doctrine" but believes someone who believes in it can be saved.
Original Sin
Dr. Jack Cottrell denies original sin, at least in the traditional sense. He believes that actually states that any original sin that might have existed is wiped out by "Original Grace" given to everyone through the death and resurrection of Jesus. Thus, original sin is theoretical only, and never has any real effect on the salvation of believers. When a person sins, they receive partial depravity. Cottrell would define partial depravity as, "no matter how evil sinners may be, they all have the ability to make a free-will choice to accept the gospel."
Temporality of God
Dr. Cottrell posits that God is temporal, although not bound by time.
Baptism
Cottrell believes that baptism is, "commanded in a salvation situation." Cottrell expands on this thought and states that baptism is required for salvation. He says, "Repentance and baptism are...obedience to the gospel, and are works in the same sense that faith is.""docs.google.com"/>
Anti-Feminism
Cottrell is the leading opponent in the Christian Churches and Churches of Christ of equality for women. In the late 1980s, Cottrell became alarmed by the incursion of feminism in the church which he believed was against God's original design for the church. He published his book Feminism and the Bible: An Introduction to Feminism for Christians in 1992. He summarizes the 358 page tome in this blog post, "How Feminism Invaded the Church"., dismissing every version of feminism, including evangelical feminism, as unscriptural. He sits on the Council on Biblical Manhood and Womanhood. The mission of CBMW is "primarily to help the church defend against the accommodation of secular feminism." As enumerated in its , CBMW is an evangelical organization that seeks to encourage women to the roles assigned to them by the Bible. Moreover, in every walk of life, men are expected to "exercise headship" while women are to "be in submission". He continued to research the topic and published two more books, Gender Roles and the Bible: Creation, the Fall, and Redemption: A Critique of Feminist Biblical Interpretation, and Headship, Submission, and the Bible: Gender Roles in the Home.
