'Weak' in the Bible

Without becoming weak in faith he contemplated his own body, now as good as dead since he was about a hundred years old, and the deadness of Sarah’s womb;

For what the Law could not do, weak as it was through the flesh, God did: sending His own Son in the likeness of sinful flesh and as an offering for sin, He condemned sin in the flesh,

Now accept the one who is weak in faith, but not for the purpose of passing judgment on his opinions.

One person has faith that he may eat all things, but he who is weak eats vegetables only.