Regarding Faith: Every time we sin, we are demonstrating, at that moment, a lack of faith/trust/confidence in God. Every time we worry, we are also demonstrating a lack of faith in God.
Verse 7: "CALLED to be saints." This speaks of Election.
Verse 13: "I planned many times to come to you (but have been prevented from doing so..." The result of God keeping Paul from going to Rome is the book of Romans. (If Paul had gone to Rome, he might never have written this letter.)
Verse 17: "...a righteousness that is by faith from first to last..." For cults or anyone who says that faith alone is not enough to save a person. This is the verse God used to bring Martin Luther to become regenerated.
Some have said that all people need to know is that God loves them; that it's not what we believe that matters, but what we do; that the social teachings of the Bible are what's important; and that doctrine merely divides. But if that were true, Paul would not have written Romans (which is a theological letter, as opposed to 1 and 2 Corinthians or Galatians, that deal with problems in the churches). The problem is not that people need to know that God loves us (many unbelievers have heard that God loves them). And yes, some people do doubt sometimes that God loves them. But the real problem is that we do not love God, just as Luther discovered. We resist God vigorously because we don't want Him to rule over our lives, and we resent any meaningful attempts He makes to do so. One person summarized Romans as "Man's Total Ruin in Sin" and "God's Perfect Remedy in Christ."