My earlier letter that one can only leave Islam with conditions applies to all faiths as well. If we live in a multi-racial and multi-religious society, we should never regard any one religion as lesser than another. The only thing that makes a religion different from another is its age.
Islam is the oldest religion in the world, founded by Adam, and it was reborn with Abraham and a second time with Muhammad. Between Abraham and Muhammad, Hinduism, Buddhism, Judaism and Christianity emerged in this order. Then Sikhism emerged after the time of Muhammad. These are the six world religions.
The conditions imposed on one leaving a religion to join another are based on universal human values, in particular the need to regard every established religion as relevant for all times. This is religious equality.
Leaving Islam should be allowed on the grounds that there is something wrong with Muslims, not with Islam. There is nothing wrong with any religion. Things are only wrong with the believers of any religion. They may be lacking in compassion, or rigidly dogmatic in interpreting the faith.
One should, as a humanitarian believing in the One God who created us all, not say anything negative about any one faith. It is the believers of a faith that are bad, never the faith.
As for Muhammad's perfection, it is to be honoured, just as true Muslims should honour the perfection of Jesus, the Buddha, the Sikh gurus and the Hindu devas. This is part of reverence for all religions as one family.
Likewise with the Quran's perfection. It is an established fact that the Quran was written by God, and not by humans.
This is not to say any other religious scripture is imperfect. This statement only means that the Quran is the only book written by God, just as Jesus is the only founder of a religion who was born to a Virgin Mother.
Every faith has something unique which in no way lessens other faiths.
As for the Sahabah (companions), they should be seen in the same light as the 12 apostles of Christianity, to cite a good example. They are revered not only by Christians but also by Muslims, Jews, Buddhists, Hindus and Sikhs for their selfless sacrifice and humanity.