'Weak' in the Bible

When Jesus heard this, He said to them, “Those who are healthy have no need of a physician, but [only] those who are sick; I did not come to call the righteous, but sinners [who recognize their sin and humbly seek forgiveness].”

Immediately the father cried out, "I do believe: strengthen my weak faith."

Watch ye and pray, lest ye enter into temptation. The spirit truly is ready, but the flesh is weak.