Real God cannot be divided. He is everything. Always and forever. If God can be divided, then He is not He. He is not I AM.
There was only one God in the Old Testament. There was only one God in the New Testament. Then Jesus rose from the dead, and the Church of the Empty Tomb, the Catholic Church, immediately began experiencing dissent. First were the Circumcisers in Acts 15. In the first century came the Gnostics in the first century, then the Montanists in the second century, Sebellianism in the third, Arianism in the fourth, Pellagianism in the 5th along with Nestorianism and the Monophysites also in the 5th century, Iconoclasts in the 7th century, Catharism in the 11th, and finally Protestantism in the 15th and Jansenism in the 16th centuries.
Jesus planted a seed, which is Catholicism. It immediately sprouted, and the main trunk of Catholicism grew strong. Some doubted and branched off. All of the great heresies mentioned above exist in one form or another today. Some are Christian, some have Christian trappings, some are not Christian at all. Protestantism has branched off into 35,000 separate faiths.
There is only one God-that’s the God of the Bible. The Catholic Church is the only Church who has been around to defend true Christian belief from the falsehoods of men. The Gnostics denied Genesis 1:31. Montanus claimed that his teachings were above the Church. The Sabellianists taught that Jesus Christ and God the Father were not distinct persons. Arius taught that Christ was a creature made by God. Pelagius stated that man is born morally neutral and can achieve heaven under his own powers. According to him, God’s grace is not truly necessary, but merely makes easier an otherwise difficult task. Nestorius claimed that Mary only bore Christ’s human nature in her womb. The Monophysites (led by a man named Eutyches) were horrified by Nestorius’s implication that Christ was two people with two different natures (human and divine). They went to the other extreme, claiming that Christ was one person with only one nature. Iconoclasts claimed that it was sinful to make pictures and statues of Christ and the saints, despite the fact that in the Bible, God had commanded the making of religious statues (Ex. 25:18–20; 1 Chr. 28:18–19), including symbolic representations of Christ (cf. Num. 21:8–9 with John 3:14). Catharism was a complicated mix of non-Christian religions reworked with Christian terminology. The Albigensians formed one of the largest Cathar sects. They taught that the spirit was created by God, and was good, while the body was created by an evil god, and the spirit must be freed from the body. Protestant groups display a wide variety of different doctrines. However, virtually all claim to believe in the teachings of sola scriptura (“by Scripture alone”—the idea that we must use only the Bible when forming our theology) and sola fide (“by faith alone”— the idea that we are justified by faith only).
Christ founded one Church in Matt 16:18-20 with himself as the foundation and Peter as its first head. Jesus knew that every man must die, and promised that the Holy Spirit would protect the true faith from all the errors man could throw at it. Christ instructed the Church to preach everything he taught (Matt. 28:19–20) and promised the protection of the Holy Spirit to “guide you into all the truth” (John 16:13). That mandate and that promise guarantee the Church will never fall away from his teachings (Matt. 16:18, 1 Tim. 3:15), even if individual Catholics might.