'Weak' in the Bible

Without being weak in faith, he considered his own body as dead (because he was about one hundred years old) and the deadness of Sarah's womb.

Now receive the one who is weak in the faith, and do not have disputes over differing opinions.

One person believes in eating everything, but the weak person eats only vegetables.

But we who are strong ought to bear with the failings of the weak, and not just please ourselves.