The Nicene Creed, our Profession of Faith,
We believe in one God, the Father, the Almighty, maker of heaven and earth, and of all that is, seen and unseen.
We believe in one Lord, Jesus Christ, the only Son of God, eternally begotten of the Father, God from God, Light from Light, true God from true God, begotten, not made, one in Being with the Father. Through him all things were made. For us men and for our salvation, he came down from heaven: by the power of the Holy Spirit he was born of the Virgin Mary, and became man. For our sake he was crucified under Pontius Pilate; he suffered, died, and was buried. On the third day he rose again in fulfillment of the Scriptures; he ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead, and his kingdom will have no end.
We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son. With the Father and the Son he is worshipped and glorified. He has spoken through the Prophets.
We believe in one holy Catholic (Catholic = Universal) and Apostolic Church (According to the doctrines of the apostles; delivered or taught by the apostles; as, apostolic faith or practice.)
We acknowledge one baptism for the forgiveness of sins.
We look for the resurrection of the dead, and the life of the world to come.
If you understand the Creed you understand the basic teachings of the faith. This is the foundation of the Church teaching.
The Catholic Church is indefectible, having no flaw or defect, in terms of its teaching what Christ said and what He meant about faith and morality. The Church has been revealed by Christ and the Holy Spirit the teachings of faith and morality.
This is why all teachings in regards to the faith can NEVER be changed and NEVER has changed. God does not change his mind because it is 21st century. The profession of faith stated above was passed on to the Apostles by Jesus Christ. On Pentecost Sunday, the Holy Spirit filled the Apostles with the Spirit and enabled them to proclaim that faith. As Jesus said in Matthew 16:17-19, “And so I say to you, you are Peter, and upon this rock I will build my church and the gates of the netherworld shall not prevail against it. I will give you the keys to the kingdom of Heaven; and whatever you bind on earth shall be bound in heaven; and whatever you loose on earth will be loosed in heaven.”
This is what Catholics believe.