The verse of the Bible that you mentioned says that women must be covered when they pray or prophesy, not every day nor in every moment of the day. This is a clear and significant distinction between the Islamic and Christian traditions. In Christianity, this tradition is meant to reflect the relationship between Jesus and his church. The husband symbolizes Jesus and the wife symbolizes the church. Hence, to carry this symbolism even further, the woman covers her head in order to express the submission of the church to Jesus Christ. Notice that the Islamic dress code is not based on a theological symbolism, but is related only to an attempt to preclude sexual desires in men: "And tell the believing women to lower their gaze and to guard their private parts and not to show their adornments except that of it which normally shows. They shall cover their cleavage with their ‘khimar’. They shall not show their adornments except in the presence of their husbands, their fathers, the fathers of their husbands, their sons, the sons of their husbands, their brothers, the sons of their brothers, the sons of their sisters, other women, their slaves, the male attendants who have no sexual desire and the children who are yet to attain awareness of women’s nakedness. They shall not strike their feet so as to reveal details of their hidden ornaments. You shall repent to God all you believers, so that you may succeed." (Qur'an 24:31)