I had a thought today.
If faith is credited to me a righteousness, ie 100% acceptable before the Lord, why do I need to walk in righteousness and not sin?
Now it began to dawn on me. If you love Jesus and dwell in Him, have a clean heart, express praise and meet needs around you, you have fellowship with God and are in a good place. Once sin comes in, things change. You dwell less with the Lord, spending time in the word and prayer becomes harder, and believing God cares is more difficult to hold on to.
If sin becomes dominant, then faith goes out the window, along with your righteousness before God.
So faith is the key to acceptance by God and gaining communion, and learning to walk in righteousness echos and enhances this relationship. Now some have argued that it is grace that keeps us acceptable, not faith. Faith would match with Pauls preaching, and also match with sanctification, walking and learning to grow with Jesus. It is the direction of travel that matters and the progress which helps maintain and reinforce faith.
The analogy with the vine also fits. If we stop abiding, we die, grow cold, loose the focus, do not desire living water, and become empty.
The grace group replace faith with grace, and make it all irrelevant what you do because it can never be lost, and does not damage what you have already gained. But in faith, if you abide in sin, you will loose your faith and its meaning will leave your heart.
Now the faith we have is a gift, given through Christ and the cross. Without life within, this faith seems to leave us.
Many christians have gone through dry periods where it all appears meaningless. Some have said they have almost become atheists. I have never gone this far myself but I know the feeling. Dwelling in the Lord changed everything though, but I think we need to explore these realities and often what we base our relationship with God on.