It's important to know what you believe. It is equally important that we teach what we know. Christians and churches have often been lazy when it comes to learning and teaching. How can we be obedient to the faith if we don't know or understand it? I am grateful for the commission of Vatican 2 and Pope John Paul the Great to evangelize and catechize.
With that in mind, here's a tidbit from the Catechism of the Catholic Church (#2087-2089):
Our moral life has its source in faith in God who reveals his love to us. St. Paul speaks of the "obedience of faith" (Rom 1:5; 16:26) as our first obligation. He shows that "ignorance of God" is the principle and explanation of all moral deviations. (Rom 1:18-32) Our duty toward God is to believe in him and to bear witness to him.
The first commandment requires us to nourish and protect our faith with prudence and vigilance, and to reject everything that is opposed to it. There are various ways of sinning against faith:
Voluntary doubt about the faith disregards or refuses to hold as true what God has revealed and the Church proposes for belief. Involuntary doubt refers to hesitation in believing, difficulty in overcoming objections connected with the faith, or also anxiety aroused by its obscurity. If deliberately cultivated doubt can lead to spiritual blindness.
Incredulity is the neglect of revealed truth or the willful refusal to assent to it.
Heresy is the obstinate post-baptismal denial of some truth which must be believed with divine and catholic faith, or it is likewise an obstinate doubt concerning the same;
Apostasy is the total repudiation of the Christian faith;
Schism is the refusal of submission to the Roman Pontiff or of communion with the members of the Church subject to him.