Preserving church unity
When Melanchthon came to Wittenberg in 1518 he admired Luther's uncompromising return to the Bible as the only source of faith. Under Luther's influence, Melanchthon himself became a precursor of the Reformation. Yet Melanchthon did not have to abandon his humanist heritage. On the contrary, the Reformation needed Humanism. Without linguistic and literary education Christians become "fundamentalist" and intolerant, he believed. An educated Christian does not break off conversation with those of other faith. All his life Melanchthon pinned his hopes on the power of communication.
And yet he experienced many disappointments on this score. In 1521 Emperor Charles V placed Luther under an imperial ban at the Imperial Diet of Worms, threatening to take forceful action against the "Lutheran" cities and princes
But because he was waging war outside of the empire he couldn't put his threat into practice. It was only in 1530 that the emperor returned and demanded that the supporters of the Reformation account for themselves at the Imperial Diet in Augsburg. On behalf of the Elector of Saxony and the other Protestant estates (classes) Melanchthon drafted a defence. In it he showed that Reformation beliefs and striving to reform the church were not new, "heretical" ideas. They are biblically founded and thus "catholic", i.e. generally Christian.
Melanchthon hoped to convince the emperor and empire of his arguments. Only if all returned to the biblical source could true unity come about. Humanist education and Reformation convictions blend impressively in the Augsburg Confession.
Here Melanchthon writes (CA 21, end of the doctrinal part) :
"This is the sum of the doctrine that is taught in our churches. Since it is clearly founded in Scripture, and does not oppose the Christian, or even the Roman Church, we think that our adversaries cannot disagree with us."