We are justified by faith. This is a legal, judicial argument that God declares, as judge, on our behalf. It is the faith, which God has given us, that is our justification to stand in righteousness in Christ Jesus before God the Father.
The Bible tells us that we are saved by grace, not by works. We are not saved by faith. This seems to perhaps be your stumbling stone.
We are justified by faith, but not saved by faith. We are saved by grace. (Ephesians 2:1-10)
In Ephesians, Paul tells us that faith is not of ourselves, but is the gift of God, which, in Romans, sets us free from guilt of sin. In Hebrews 12, we see that this faith, given to us by God, is authored and completed by Jesus. Therefore, we have no cause to boast. Everything that we are, before the throne of God, is entirely because of Christ Jesus.
Hopefully, the lightbulb will turn on for you. I am not sure I can make it anymore simple than this for you.