The Bible should be the only source of Christian life.

Christians, Catholics especially, believe that the bible is one main source of our Catholic life. However it is part of a two step part of our Christian, and most other religions life.
We, the Catholic people, believe in sacred tradition and scripture, tradition is our everyday life, and scripture is the Bible. The Bible is a source in which we can follow, however, Jesus wanted us to have free will, which makes us allowed to sin, even though we should try to avoid sin.
The Muslims have the Koran, which tells them that they have to visit the Kaaba stone once a life time. The Koran does not say to go to the Kaaba, the Muslims do it by TRADITION, that's all to say for now.

According to what I've been taught by the teachings of Martin Luther, "sola scriptura" (by scripture alone) is the only source of divine revelation.We also reject Sacred Tradition and the pope's authority because of this.Every Christian has the ability to understand Scripture by God's Grace.

Lutherans have different beliefs than Catholics. Martin Luther said that we could understand scripture by God's grace, and you agreed, quote for quote, "Every Christian has the ability to understand Scripture by God's Grace" . This means that we need God's grace to understand the scripture. We can get God's grace only by sacred tradition, therefore, you contradicted yourself.
Also, you said to try to stay away from sin, but we need to have tradition to tell us what is good and bad. Sure, the bible tells us all what we should do, but God also gave us things to do through the saints, who are not part of the Bible. St. Joan was prudent when she was burnt, and we have to be prudent, or careful to get to Heaven. Without prudence, we could not be careful around other people, such as if they were going to kill you if you didn't sin, you don't sin because prudence tells you not to. Prudence is not described in the bible as what we think of it today. It says that prudence keeps us with God, which it does, don't get me wrong, but it is not clear about how it keeps us with God.

With this round forfeited, Muzicfreek has given me nothing to go against, so good luck.