Why was there tension between Catholics and Protestants?

The Catholic church believes that it is the only true church on earth, and that all other Christian churches broke away from the Mother Church. They claim that if they are right then there is no need for the other churches.The Protestant churches came about because of the strict dogma of the Mother church and the demand of payment to have sins forgiven. The Protestants (Protesters) believed that only God could forgive sins through earnest repentance and by good works. One other fact is that the Mother church believed that only the clergy could read the Bible, so Bibles for the common people were banned.