They shouldn't, but I think they do. From the past, people often had to believe what they were told to believe, or they were killed or persecuted. I was reading about the King that Christianized Norway. You were Christian or else! People want to belong, so they go along with creeds, some may speak to a person's heart. There are many reasons.

[Please note: A very similar question appeared in this forum and the following is a copy of my response there.' The English word 'creed' comes from the Latin word 'credo' or 'i believe'. They came into use long after the Bible was completed, during the period of the Great Apostasy. Many scriptures warn of this time, including 1 Timothy 4:1-5 and Acts 20 (around verse 28). Some of the creeds have some support from the Bible and most of them incorporate at least some manmade teachings. 2 Timothy 3:16 tells us that all scripture is inspired of God and beneficial for teaching, reproving, setting things straight and disciplining in righteousness that the man of God may be fully competent, completely equipped for every good work. Everyone must make his own decision on this matter, but if you accept creeds as the higher authority, you are disclaiming the truthfulness of the Bible. Triogods stated that the foundation of Christian belief is the trinity. I respectfully disagree. He's right in stating that the trinity is not found in the Bible. That is for very good reason. If it were the foundation of Christ's teaching, you can be sure that he would have spent time explaining it and that the apostles would have given it thorough coverage. Read the model prayer in Matthew 6:9-13 and you will find that the 2 priorities are sanctifying (hallowing) God's name and the coming of the Kingdom. Read the Gospels and you will find over and over that Jesus preached the Kingdom. (Luke 9:1; Matthew 13) A key feature of the last days is that Christians would preach the "good news of the Kingdom" (Matthew 24:14; Mark 13:10). Daniel 2 (especially verses 44,45) and chapter 7 indicate the importance of that Kingdom, even in pre-Christian times. Read the last half of 1 Corinthians 15; Revelation 5:9;14:1-4. In John 15-17, Jesus repeatedly tells of declaring the Kingdom and making God's name known. Titus 2:4 tells us that God took out a people for His name. The foundation of Christian belief? The glorifying of God's name and submission to his Messianic Kingdom. Here's where every reader needs to make a choice: Believe the creeds, based on the trinity or the Bible which doesn't mention it once. Believe the creeds which avoid using God's personal name completely or the Bible which anounces it boldly about seven thousand times.