Looking unto Jesus the author and finisher of our faith… – Hebrews 12:2

And straightway the father of the child cried out, and said with tears, Lord, I believe; help thou mine unbelief. – Mark 9:24

Have we so much of faith that God can largely bless us? The comfort is that, if we have it not, the author of faith can give it to us, and if we have it in scant measure He can increase our faith. Is not this a solid reason why you and I should take heart? You who do not believe that missions will succeed; you who readily become discouraged and discourage others; I beg you go home and seek more faith. We cannot go down to the battle with such soldiers as you; you do but encumber the host. The men that lapped are the only ones that Gideon will take to war. Send the fearful ones to the rear and let them take care of the baggage, so that when the battle is won they may have a share of the spoil, according to David’s law. For actual service and warfare we must have men of faith. Cromwell found that when his men came dressed in all sorts of suits and colours they were apt to injure one another in the melee, and so he put them all in uniform. The uniform of the Prince Immanuel is faith: no man may call himself a soldier of the cross who hath it not. This is the victory which overcometh the world, even your faith.

Let us hear the scripture, as it says, “Hearken! “If you have faith as a grain of mustard seed, “Hearken!” for you may hear the Sabbath bells ringing in the everlasting peace, and angel songs welcoming the reign of grace over all nations. Let the ears of deaf unbelief be unstopped, for the whole earth echoes with the praises of the Lord. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1596.cfm