Faith is an essential part of Christianity, we cannot say that we are Christians and have no faith. Even the apostle says that without faith it is impossible to please God. Faith is vital because we cannot see the One we serve, but we believe in Him, in His Word and in His powerful works.
The apostle Paul wrote to the Corinthians:
6 Therefore we are always confident, knowing that, whilst we are at home in the body, we are absent from the Lord:
7 (For we walk by faith, not by sight:)
2 Corinthians 5:6-7
We live always confident, we always have faith, although this does not mean that in some moments of our Christian life we will not doubt or feel that weakness, but after those moments it is that our faith is polished like gold in the fire, those moments are those who teach us that our trust only comes from God and that we have no one else to go.
In the Bible there were many men of faith, who believed in God in the darkest valley, and never doubled, because they lived confident every day, because they knew who they believed in. We must know God in His essence and not doubt that He is Powerful to keep us firm until the end.
We do walk by sight but by faith, we do not only see what happens in this physical world, but we can see beyond all this, we can see a city, a heavenly homeland that is awaiting for us, that Christ prepared for us, where we will not need of no earthly thing, but we will dwell together with God for an eternity.
Beloved brothers, this is a good battle, it is an incredible battle and we urge you to keep fighting, to continue believing, for God is on your side as a powerful giant to keep us firm against adversity.