Weak faith that gropes for some footing for reason to stand on tries desperately to reconcile God's promises and human reasoning. And weak faith asks many questions. When Christ says, "Give ye them to eat," His disciples ask in return, "Shall we go and buy two hundred pennyworth of bread?" Mark 6:37. As if Christ's bare word could not spare them that cost and trouble! "Whereby shall I know this?" says Zacharias to thee angel, "for I am an old man". Luke 1:18.His faith was too feeble to stand up to such wonderful news.
The more contented the Christian's heart under the changes which providence brings on his state and condition in the world, the stronger is his faith. Weak bodies cannot tolerate changes of weather as well as healthy ones. Heat and cold, fair and foul weather cause no great change in the strong man's constitution. But the weak person complains of them. Thus strong faith can live in any climate, travel in all weather, and handle any unpredictable condition. "I have learned, in whatsoever state I am, therewith to be content," says Paul Philippians 4:11. Unfortunately, however, not all Christ's followers are like Paul in this; in weak faith has not yet mastered this hard lesson."
Quoted material from, ”The Christian in Complete Armour Daily Readings in Spiritual Warfare” by Gurnall and James S Bell. http://www.moodypublishers.com/pub_productDetail.aspx?id=41823&pid=53617