"It is clear Madison changed his later beliefs from his earlier actions, but labeling Madison a theist because of his contradictions and use of philosophical terms rather than biblical ones isn't sufficient justification." (From "http://ourfoundingtruth.blogspot.com/2007/07/was-james-madison-christian-or-theist.html)
Historians have claimed that the Founding Fathers were theists, not outright Christians in their beliefs and habits.
Thomas Jefferson styled himself a "Christian man", though he expurgated the intolerable miracles in a deist demystified version of the Bible, and refused to accept the essential arguments of the Christian faith, i.e. the divinity of Christ, His death, and His redemptive resurrection.
James Madison, the Father of the Constitution, did champion the deist Thomas Jefferson as a mentor in political matters, but not religious ones.
Madison even entertained plans to enter seminary after his studies at Princeton before taking up law.
He also spoke highly of the need for Christian faith and a fervent dependence on God.
Yet which God was Madison referring to in his later writings? Was it the Deist God, whom those followers claimed was a general spiritual manifestation made specific by the cultural traditions of the several religious practices throughout the world? Or was Madison referring to the God revealed in the Bible, as YHWH to the Jews, then full revealed to the world through His Son Jesus Christ and indwelling in all believers by the Power of the Holy Spirit?