We might answer the question of “why do we need faith” in many ways, and one of them is by contemplating the differences between good things and bad things.
In order to create a good thing or make a thing good, it usually takes time. Some things need the accumulations of long time efforts to become good, and some good things even need to be repeatedly done without a final ending, such as breathing, eating, sleeping, and exercising for a living person. But bad things in general could be done instantly.
That’s the way how God created the laws of the universe, but it does not mean that God could not make good things instantly. From time to time, God makes good things instantly at his own sovereign will. But in general, because of all the natural laws and subjective logical rules created by God, good things would normally take time to come true, which is how God makes it. We might even remotely relate this facet of the nature of universal existences to the fall of Adam and Eve as described in the book Genesis.
We know that God is good all the time, and devil is bad always. Now we also know that good things normally take to time to come true, but bad things could be done instantly in general. Then we might understand why God needs us to be patient.
In order to be patient while God is doing good things for us, we need to be faithful, which means that we shouldn’t only see what is visible, but need to believe that God is working behind the scenes for our good. Otherwise, we might feel that God is too far and devil is too close since God is doing good things that take time in general but devil is playing an easy game of doing nasty destructive things that could be done instantly in general.
One important thing for us to be patiently faithful in God is to be aware that God has a plan for the children of God, for which we could have various promises from God in addition to our eternal promises in heaven from God.
Thanks to God!