The sons of God are manifested in our fleshly bodies by faith. This is done in part, until we reach the fullness of the stature of Christ, through the power of comprehension. Paul said that you might be able to comprehend the heights, the depths, and the widths. So, we must earnestly contend for this faith which was once delivered unto the saints. This means perfection if we don't waver.
Maturity comes by perfect works of obedience, a clear conscience, and works of righteousness.
Works make faith perfect. James tells us that we must be partakers in the sufferings and self- denial of Christ, so that we might become compassionate, enabling us to feel the infirmities of others. By this, we develop a faith sufficient to meet their needs. Faith works by love, which is the bond of perfection, because it fulfills God's laws by thinking no evil, thus eliminating condemnation from the heart, which, in return, releases faith, so that it might go into action in our behalf as it commands God concerning the work of His hand. When you fear, you waver.