Luther’s goal was to reform the church (hence the term “reformation”), not to split it or start a new one. The split occurred when he was excommunicated. Leo X btw was a head of the Medici family who ruled Florence and used the power of the Papal States to attack enemies of his family regime. He is best known for selling indulgences to raise money for the new St. Peter’s Basilica he was building. This practice was one which outraged Luther.