Sorry, but I disagree. SALVATION is the most important one to get right, and this is where Catholicism goes against the scriptures. They teach a different way to be saved.
And tragically, the Protestantism and the big-bang of denominations that followed, rejected the form of catholicism, but kept its very essence, its poison, its pagan/juridical understanding of salvation. Instead of wanting to unite with God, people want to escape (to be saved from) the hands of God. No wonder atheism was born in the western world.