>Why do Catholics and Protestants fight
It's doctrinal. Deal breaking dogma. My best friend is a Catholic, I'm a Pentecostal. We get along fine. When discussing our beliefs, it gets heated, almost ended our friendship a couple times, now we just banter and share memes. As far as beliefs are concerned, Catholics and Protestants have a ton in common, and have the potential to learn from each other in a real profound way. It's as soon as you get to justification, faith vs works, the priesthood, baptism– the real fundamental things that makes someone a follower of Christ; it's not about getting along, Catholics and Protestants can do that just find so long as they understand each others beliefs. It's when they begin to work together that it becomes impossible. Protestants are obsessed with not being deceived. They're constantly vigilant against believing the wrong thing.
This is likely due to the fact that it has evolved so many times at so many points in time. Lordship salvation, "easy believism", calvinism vs arminianism, once saved always saved, the nature of sin, how much sin does it take to cut you off, does sin cut us off at all, does it break fellowship or put us in true danger, prosperity gospel and seeker friendly heresies, near death experiences sowing distractions towards heaven, and near death experiences of people going to hell, visions, prophesy, and a myriad of minute doctrinal issues that split believers down to the individual. It causes Protestants to be inherently distrustful towards any other person of faith, especially when they don't understand the other persons beliefs due to the attitude that they don't need to because it's heresy. Naturally, Catholics look at this and want nothing to do with Protestants. Even if that weren't true, the extreme orthodoxy and legalism found within the Catholic Church makes them skeptical against any sect not of their own by virtue of their own orthodoxy, and the imploring never to venture outside the borders of their dogma.
This is why the two groups can't get along, just to scratch the iceberg. But my friendship with my Catholic friend has caused us to find the remedy to this feud altogether, and that's the fact that among this labyrinth of dogmatic beliefs, it's easy to miss the most important figure of them all. Jesus Christ. Chances are, if you're a Christian, and you believe anything about the Bible, another Christian is going to call you a heretic. It's utterly unavoidable. Who then can be right? Only one is. I'll tell you who the true Christian is, and that is the Christian who in their own confusion and earnest seeking of the real Jesus, realizes the sufficiency of Christ alone and the core message of the entire Bible which is built on a solid foundation of trust of the Lord. The Lord Almighty is worthy of our trust. He is trustworthy. If you believe in the gospel, and you place your trust in him, and earnestly seek to do his will, he is faithful to show you what his will is. The problem with Christianity is that because man is blind, he tries to find ways to see through the diligent study of scripture on his own accord, coming to his own conclusions and trusting the words of men instead of trusting the Living Breathing person of Jesus Christ who was and is and always will be the Word. The Way, the Truth and the Light.
Making the decision to actually trust him is what actually separates the true believer from the false believer. The sheep from the goats. Putting your trust in the hands of the Most Trustworthy will never fail the earnest heart, because God is faithful. His eyes search to and fro along the Earth for the heart who genuinely seeks him. It isn't the good Catholic or the good Protestant who will enter the Kingdom. It isn't the one who relies on their works per sae. It is the one who becomes like little children, trusting the Lord as a child, eager to do his will as a child, delighting in the praises of his Father as a child. This is who will be saved, and this is who you should be associating with and getting along with. In the spiraling hallways of manmade doctrine, in my deepest confusion and fear of what is right, this is the only conclusion I have come to. This is the only conclusion any earnest heart who desires the Lord will come to. And it's in this utter abandon of pride and self righteousness that one realizes the true sufficiency of Christ.
God bless