It might be true that the Guru Granth Sahib might be the only Guru, but what use is it, if we know all the verses by heart and can repeat/memorize them without actually practicing what is preached? While the Granth Shaib might be in its purest form and has not been altered, it is the living Guru that can help us achieve the goal of moksha and guide us through step by step just like how a mother guides her child through the initial stages of walking. A child simply cannot read a book about walking and start walking on his own can he? The Guru Granth Shaib is filled with beautiful teachings that are hard for human beings to follow and practice unless one is a renunciant/sadhu. Unless we know how to apply in the right way what the Guru Granth Sahib is teaching to us, in this age of Kalyug(a), when we are not living in the age of Lord Ram and Krishna(Satyug), it is extremely difficult to attain liberation from samsara just by following a text. Not only do we need theoretical knowledge, but we need practical knowledge, and it is a living master/guru who is able to provide that to us and we should be thankful for that blessing. Simply put it, YOU CAN definitely follow the path of the Guru Granth Sahib and attain your goal, but it is definitely harder and requires an immense amount of penance and self-discipline to achieve, and this could very well take many births and rebirths. The presence of the living master/guru with the gift of Naam and the sound current, makes this process much more bearable and attainable in this lifetime alone. Both paths are possible. You choose if you want to tread the arduous journey back home to the Lord, or chose the path with Grace of the Lord. Religion, or for that matter faith, has got nothing to do with anybody else other than one’s personal relationship with the divine, and nobody has the right to intrude in this unique and initimate bond between the disciple/seeker/son and the Master/Guru/God. It is a matter of personal choice and one should live and let live. One’s past karmic account determines the soul’s connection to a certain faith/religion/sect in this birth and each one of us has our own karmic accounts to clear and pay off – so let us not judge as to which religion/faith/path/sect is more right or superior than another and let us just focus on humanity, love and morality – simply being human.