Yes, Protestants are Christians, and so are Catholics. They both believe in the divinity of Jesus and in the Trinity, and many Protestant denominations practice the Sacrament of Baptism as well as other ordinances. I think the most essential dogma of both religions is quite similar. But there are differences between the religions with regard to doctrines, practices, and customs. The concepts of sola fide and sola scriptura come immediately to mind, although I realize not all Protestants interpret these ideas so simply. Perhaps one might say the mainstream of Protestants as well as Catholics have the same Christian faith, but not exactly the same religion. So do (most) Quakers hold the same Christian faith, but in their case surely not the same religion as either Catholics or Protestants; while Mormons and Jehovah’s Witnesses take us beyond even the same Christian faith. Yet each of these groups regards itself as Christian and, even more, the true Christian faith. Although Catholics may consider Protestants as Christians, they, for the most part, do not regard them as Christians who possess the full Truth of the Church, to put it nicely. Many in fact regard them as heretics, to put it more bluntly. (Some Orthodox Jews likewise consider non-Orthodox Jews–Conservative and Reform–as heretics, but still regard them as Jews.) From the typical, non-scholarly Jewish perspective, Catholics and Protestants are grouped together as Christians, and their dogma differs sufficiently from Judaism for many Jews to regard them both as outside of the Jewish faith, as well as religion. However, for both the Jewish and the Christian scholar, there are enough significant similarities with respect to both faith and religion between Protestants, Catholics, and Jews so as not to separate them completely from one another. The most obvious is that they all are monotheistic religions, which share a common religious history.