God revealed Himself in Jesus. That didn't take away man's ability to sin. Man's corruption can't take away from God's revelation. It can be a temptation not to recognize God's Revelation, but it can't negate what God revealed through Jesus Christ. It is a fact that all people, even authority figures in the Catholic Church, sin. To use sin, as an excuse to deny God's revelation through Jesus, only compounds the sin by creating more sin. It does not institute a religion based on the true Revelation of Christ.
Therefore, according to the Catechism of the Catholic Church Part 1, Section 2, “Whoever says “I believe” says “I pledge myself to what we believe. Communion in faith needs a common language of faith, normative for all and uniting all in the same confession of faith.”
Creeds came about through God’s revelation, not man’s opinions, and they clearly state the belief system chosen by those who accept them. Just as immigrants to America become citizens and live by the Pledge of Allegiance, Catholics adhere to the teachings of the Church stated in our creeds.
Catholics have 4 creeds that express our beliefs and profess our faith. The Apostle’s Creed is probably considered the most common, along with the Nicene Creed. However the Athanasian and Trentine also profess our beliefs.