It was in jest that I once said to an Arab friend in Dubai, "You guys are lucky. Your Prophet permitted you four wives." He replied in all seriousness, "You are wrong. He did not 'permit' us. He restricted us to four wives." He then went on to explain that in the social anarchy prevailing in the Arab peninsula at that time, what Prophet Mohammed preached was nothing short of revolutionary. The veil, too, was an attempt to protect women from male depravity in that free-for-all society, "Just like taboos and customs prescribed by other religions around the world, which were always dictated by the need of the times," he added.
Indeed, the five Ks of the Sikhs, of which unshorn hair (and the turban that goes with it) is one, were also laid down by the Guru to meet the requirements of an ascetic army of defenders of the faith. But what was revolutionary or deemed necessary centuries ago may not be relevant to our lives today. To literally interpret and strictly enforce injunctions given in particular circumstances will inevitably lead to conflict and dissent.
The western world faced this problem in the 15th century with the Reformation. The papacy resisted this 'apostasy', which led to a schism in the church. But the Reformation gave those who differed an alternative while still subscribing to Christ's teachings and divinity. It strengthened Christianity in the long run because those who dissented could still call themselves 'Christians'.
Similarly the reforms by the Brahmo Samaj and Arya Samaj in India swept away many inequities of Hindu practice, which may have had some arguable raison d'etre when originally instituted, but which seem unfair or unnecessary in the modern context. They gave Hindus another option within the fold. Such reforms do not alter the basic moral code of each creed. But they become necessary as circumstances and ideas change. It is in this context that practices and customs, such as the Catholic stand on contraception or the use of the veil by Muslim women could be reviewed.