It is in our weakness that we most clearly experience God's strength. It's in the Bible, II Corinthians 12:9, NIV. "But He said to me, 'My grace is sufficient for you, for My power is made perfect in weakness.' Therefore I will boast all the more gladly about my weaknesses, so that Christ's power may rest on me."
We should encourage those who are weak. It's in the Bible, Romans 14:1, NIV. "Accept him whose faith is weak, without passing judgment on disputable matters."
God can use those who are weak if they stay close to Him. It's in the Bible, I Corinthians 1:27, NIV. "But God chose the foolish things of the world to shame the wise; God chose the weak things of the world to shame the strong."