I was raised a Protestant in the Evangelical Church of America, which I attended (along with a closely-related Wesleyan church) for over 10 years. This was back in the "dark ages" commonly referred to as the 1980s, prior to the time of the Internet. I had no access to any Catholic teaching and all the Catholics around me were cold to lukewarm. They came across as "going through the motions." Then, there were the lies, lies, lies, and then more lies -- "The Catholic Church, Whore of Bablyon," the list goes on and on. In spite of all of this, I was deeply troubled by all of those "Catholic verses" in the Bible, whole books of which I used to memorize for church camp in the summer. I had absolutely no access to any of the writings of the pre-Nicene (or post-Nincene) Fathers of the Church, no access to any of the ecuмenical Councils, the Summa, etc. I think that a significant number of Protestants are ignorant and/or do not like the moral teachings of the Church (abortion, contraception, ɧoɱosɛҳųαƖity, etc.), which is why they persist in their errors and heresies.
One thing that deeply troubled me about my Protestant theology was the fate of infants who died without Baptism. We were taught that they went to Heaven. I remember arguing with my pastor's wife, "Well, what is the point of being saved? It would seem better to die in one's infancy and go to Heaven then make it to adulthood and have to be 'saved' especially if one was Muslim, Buddhist, etc." She did not have an answer to this conundrum.