Did you know that the phrase Sovereign Lord appears 298 times in the NIV? Do you know what it means? It means that God is in charge and there is no other authority that God must contend with. God is sovereign and he is the only one.
Why should you believe what Jesus said? That is a very good question. Why should anyone believe anything that Jesus said? I think that this is the question of questions. This is the most important question that you can answer, if in fact, that you can answer it.