It is faithful to rely on the saving work of Christ on the Cross.
It is faithful to know you are only worthy of salvation though Christ’s mercy and sacrifice. It is prudent to know you need to continue to try to be worthy of that gift every day of the rest of your life. It is persevering to put what you know about Christ into action.
Christ called the Apostles to action. He wanted them to live His teachings and pass those teachings on to others. He said, “DO this in memory of me.” Not “Know this in memory of me. “
St. Paul also made it clear that of faith, hope and love, the greatest was love. Love is action.
In the beginning was the Word, but He didn’t just stay the Word. He became flesh and lived and breathed and acted and loved. True love and faith requires action. The greatest love was put into action by Christ’s dying on the cross. And Christ reminded us that greater love hath no man but to lay down his life for a friend. Action is the greatest proof of love.
Christ already loved us infinitely. Why did He feel He had to take the action of dying on the cross? Because love, acted upon, is the greatest form of love.
You can see that the Catholic understanding of faith lived in action is closest to what Christ himself did. He didn’t just talk about it.