It is said that there is a hadith, which states that women are deficient in Religion; is it so?

Let us first look at the translation of the hadith.

Narrated Abu Said Al-Khudri: Once Allah's Apostle went out to the Musalla (to offer the prayer) o 'Id-al-Adha or Al-Fitr prayer. Then he passed by the women and said, "O women! Give alms, as I have seen that the majority of the dwellers of Hell-fire were you (women)." They asked, "Why is it so, O Allah's Apostle?" He replied, "You curse frequently and are ungrateful to your husbands. I have not seen anyone more deficient in intelligence and religion than you have. A cautious sensible man could be led astray by some of you." The women asked, "O Allah's Apostle! What is deficient in our intelligence and religion?" He said, "Is not the evidence of two women equal to the witness of one man?" They replied in the affirmative. He said, "This is the deficiency in her intelligence. Isn't it true that a woman can neither pray nor fast during her menses?" The women replied in the affirmative. He said, "This is the deficiency in her religion." (Sahih Bukhari Volume 1, Book 6, Number 301)

Abu Sa'id al-Khudri reported that the Messenger of Allah (may peace be upon him) used to go out on the day of Adha and on the day of Fitr and commenced the prayer. And after having observed his prayer and pronounced the salutation, he stood up facing people as they were seated at their places of worship. And if he intended to send out an army he made mention of it to the people, and if he intended any other thing besides it, he commanded them (to do that). He used to say (to the people): Give alms, give alms, give alms, and the majority that gave alms was of women. He then returned and this (practice) remained (in vogue) till Marwan b. al- Hakam (came into power). I went out hand in hand with Marwan till we came to the place of worship and there Kathir b. Salt had built a pulpit of clay and brick. Marwan began to tug me with his hand as though he were pulling me towards the pulpit, while I was pulling him towards the prayer. When I saw him doing that I said: What has happened to the practice of beginning with prayer? He said: No, Abu Sa'id, what you are familiar with has been abandoned. I thereupon said (three times and went back): By no means, by Him in Whose hand my life is, you are not doing anything better than what I am familiar with. (Sahih Muslim Book 004, Number 1931)

As it is clearly stated in this hadith, Prophet Muhammad (peace be upon him) explained, Womens being deficient in religion with incapability of praying and fasting during their menses. This state of being exists in the creation of women. Each woman menstruates in certain days in each month. They cannot perform some of their ritual prayers; they are exempted from some of the religious exercises but some missed prayers can be compensated later.

A woman cannot perform namaz (ritual prayer practiced five times a day in supplication to God), fast, or tawaf - (is one of the Islamic rituals of pilgrimage) which is farz (obligatory religious duty for all Muslims) during Hajj (pilgrimage to Mecca) when she is having menstruation. While she is able to compensate fasting and tawaf she is exempted from namaz. A woman that cannot perform those prayers while she menses, keeps herself separated from those responsibilities even it is for a certain time. As far as can be seen, there are no deficiencies in the living of her religion. Because namaz, fasting, and hajj are the three fundamental parts of the five basic principles of Islam, so women that cannot perform some prayers in certain times are more deficient in religion than men.

It is to say, this deficiency is comparative. A Muslim man that can perform his namaz each day of the whole year, and that can fast during the Ramadan is more perfect than a woman is; and she is inadequate in doing those prayers. For instance, a woman who menstruates for seven days every month; by not performing three months namaz her religion becomes deficient compared to that of a mans. However this deficiency is not a matter of quality, it is a matter of quantity. That is to say, she, by not performing namaz in that time period fulfills a farz; if she performs, it is haram (used in Islam to refer to anything that is prohibited by the faith).

Therefore, women are performing a kind of worship even while not performing namaz; they still obey Gods ordinance, so they will gain a gift from God in the hereafter.