Many quote verse 16 in a vacuum. We utilize it the same way we do John 3:16. It has been dumbed-down to a salvation/altar call verse. But Paul quotes it in the context of preaching the Gospel to the Romans. The Romans who were already "saved" and in church.

To Paul, faith wasn't something we used at an altar call. It IS something that we utilize each and every day of our lives. Faith doesn't just get us saved. It keeps us saved and in God's favor.

Romans 1:15-17