'Strong' in the Bible

For, "His letters," they say, "are weighty and strong, but his bodily presence is weak, and his speech is despised."

Therefore I take pleasure in weaknesses, in injuries, in necessities, in persecutions, in distresses, for Christ's sake. For when I am weak, then am I strong.

For we rejoice when we are weak and you are strong. And this we also pray for, even your perfecting.