Although not as well known as his Tudor sovereigns or as Reformers such as Luther or Calvin, Thomas Cranmer's role in Anglicanism and English Protestantism is very important. He lived in a turbulent period when the medieval western church was breaking up into various movements and bodies. His life, his ministry, his liturgical work, his theology, and his death were part of this turbulence. He was an academic who became involved in the struggles of ecclesiastical and secular politics.
Unfortunately, Cranmer really believed that kings and princes were divinely appointed instruments for ruling the church. Such a view led him to many compromises, and in his last days, Cranmer was confronted with the dilemma of choosing between loyalty to his Queen and loyalty to his understanding of Scripture and Christian faith. Under pressure, Cranmer went back and forth in his statements on certain theological details, but in the end, he affirmed his Reformation convictions and died at the stake as a Protestant martyr on 21 March 1556.
Theologically, Cranmer appears to have passed through several phases. At different times, his views had affinities with Renaissance Catholic, Lutheran, and Swiss Reformed teachings. Nevertheless, there seems to be a consistent underlying theological base in his thought, and he passed this thought on through the Book of Common Prayer, the basics of the Anglican Catechism, the Articles of Religion, some of the Homilies, and his personal influence upon his Elizabethan successor, Matthew Parker.
What is Cranmer's theological base? It is three-fold: loyalty to Scripture, respect for ancient catholic tradition, and rejection of some medieval Roman developments. Cranmer tried to follow Scripture and the ancient Church Fathers while rejecting universal papal authority, medieval theories of the Mass, and the cult of the saints. All of his private opinions were not accepted as official Anglican positions, but Cranmer did pass on a heritage for Anglicans. In his generally reformed principles, he was followed by Parker, Jewel, Hooker, and countless other Anglicans.