First, is the Catholic Church, also known as the Roman Catholic Church or the Western Church.
The meaning of the word Catholic is “Universal”, that’s why sometimes we hear the Catholic Church called “Universal Church”. The Catholic Church was founded by our Lord Jesus Christ in 33 A.D. through Saint Peter the Apostle, who is also the First Pope (Matthew 16:18). After Christ ascend into heaven and the Descent of the Holy Spirit, Saint Peter and the other apostles started their ministry. The teaching of Christ and the apostles still continues today in the Catholic Church. And the teaching of the Catholic Church is from the Holy Spirit, one of the Three Persons of God. The Head Catholic Church’s is our Lord Jesus Christ, but he has a representative here on earth which is the Pope, the Vicar of Christ. The faith of the Catholic Church is according to Scriptures and Oral Traditions. Oral Traditions is the teaching from the apostles and the early Christian fathers that was not written or documented. The Catholic Church also teaches us that we will be save by faith with good works (James 2:24).
Next, is the Orthodox Church, also known as the Orthodox Catholic Church or the Eastern Church.
The meaning of the word Orthodox is “Correct Worship” or “Right Belief”. The Orthodox Church was once part of the Catholic Church, but it was separated in 1054 A.D. One of the reasons was that they did not agree on the leadership of the Pope. Most of the beliefs of the Orthodox Church is similar to the Catholic Church, especially the Traditional Catholic. For example, The Orthodox Mass is similar to Catholic’s Tridentine Mass. But they don’t give adoration to the Blessed Sacraments. They also believe in Scriptures and Oral Traditions, and Faith with Good works. Some of the differences between the Orthodox and the Catholic are: the priests can marry, they have no pope, only patriarchs that have the same ranks and they don’t accept Catholic’s Marian dogma like the “Immaculate Conception”.
The last one is the Protestant Church.
The Protestant movement was started by Martin Luther, a former Catholic Priest who protested the issues of the church. He separated himself from the church and instituted his own church in 1517 A.D. He preached heresies to the people like everyone can have their own interpretation of the Bible. This resulted to the more branches of Protestantism, like the Methodist, Anglicans, Mormons and especially, the popular Protestant churches today, the Born Again Christians. Protestant churches do not have a united body of beliefs. Some of them have Masses, some don’t have. Some of them believe the Holy Trinity, but some believe that there’s only one person and Jesus and the Holy Spirit are not God or part of God. Some believe that if you joined their sect or church, you will be saved, disregarding the teaches of Christ and the apostles. There is one belief that is shared by the protestant churches: the Sola Scriptura o Scriptures Alone, disregarding the Oral Tradition by the Apostles and the first Christian Fathers. They also believe that they will be saved by faith alone, without doing good works, disregarding the teachings of James 2:24 of the Bible.
If you are asking which is the true church among these three? Definitely it’s the Catholic Church, the one and only Church that Jesus Christ build. And God will never abandon His Church.