Actually, there is no difference, in my opinion. A Christian is simply someone who follows Jesus Christ. So, a follower of Jesus who is Roman Catholic isn’t really different than a follower of Jesus who is Protestant – as long as they are both truly following Jesus.
The question, however, is probably meant to be asked this way: what is the difference between the Roman Catholic faith and the Protestant faith? I think the answer is relatively simple.
In short, the difference between the two can be boiled down to one word: Authority. Roman Catholics and Protestants differ in terms of what they each view as authoritative in the life of the Church. To understand this difference, we would first need to recognize some things that Roman Catholics and Protestants agree upon.
First, Roman Catholics and Protestants recognize that Jesus did not write down any commandments Himself. (There is an early legend that suggests Jesus wrote a letter to the king of Edessa. However, the alleged letter has not survived, and I believe that most scholars really doubt the story.)
Secondly, Roman Catholics and Protestants agree that instead of leaving behind an autobiography, Jesus commissioned His disciples to convey His teachings. These disciples Jesus named “apostles” (Luke 6:13), which means “one that is sent.”
Being commissioned by Jesus, the apostles had the authority to teach and interpret the words of Jesus. Roman Catholics and Protestants would agree that the teachings of an apostle are binding and authoritative in the Church. So, why are there still differences between these two movements which consider themselves Christian?
Well, the difference really begins with the death of the apostles. As the original apostles passed on, questions would be asked, like: what does the Church do when the apostles are no longer with us? Who is our authoritative teacher? Who gives us the words of God?
The Roman Catholic Church believes that Jesus foresaw this problem and addressed it with a concept that is known today as “apostolic succession.” This concept teaches that as the original apostles died, their authority in the Church would be passed on to new apostles. Down through the years the Roman Catholic Church maintains that they have an unbroken line of apostles who were appointed to replace the preceding apostle. In this way, the Church is never without the authority of an apostle. The authority of Jesus is vested in these apostles, whose teachings are binding for the Church.
Protestants, on the other hand, do not hold to the concept of apostolic succession. Generally speaking, Protestants believe that Jesus commissioned the apostles to teach and make disciples. A number of these apostles (or people very close to the apostles) wrote letters that contain the teachings of Jesus. The letters that have survived to this day – and understood as apostolic – make up the New Testament. These written documents – and no other – are binding for the Church.
Some passages of scripture that are of interest to this subject would be: Matt 16:13-19, Matt 18:15-20, and Acts 1:15-26 (there are others, too). If you study these passages and believe that Jesus was establishing apostolic succession, then you might find the Roman Catholic Church appealing. If you read them and do not find the concept supported, then Protestantism might be for you.