Sat Gurus
Soami Bagh 

Huzur Maharaj: "Surat Shabd Abhyas consists in listening to the Shabd (Sound) coming from the Heavenly Spheres above, and thereby reaching the Original Abode from where Shabd manifested in the beginning. In other words, by catching hold of the thread of Shabd, the Surat (spirit) should go on ascending from one region to another." 

Maharaj Saheb:  "The methods of devotion and training prescribed in the religious system [of the Radhasoami Faith] we are explaining represent three different forms of spiritual exercise... The three forms of the exercise are: (1) Utterance of the spiritual name by the spiritual current, (2) Contemplation of the spiritual form, and (3) Attentively listening to the Spiritual Sound (Shabd)." 

Babuji Maharaj: "He who has escaped from Mana and Maya (mind and matter) can also save others from them. Such a one is Sant Sat Guru. Unless He is met, whatever activities are performed in the name of spirituality will only result in greater and greater attachment for the objects of Mana and Maya.  None except the Sant Sat Guru can turn it inwards." 

Soami Ji Maharaj: “Know that the very starting point of Radhasoami Faith is the final goal of all other religions.”; The August Founder had said to "practice Surat Shabd Yoga wholeheartedly", and that “those who have turned their back on Meditation will suffer for their negligence."  
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“So long as Spirit does not catch hold of (inner) Sound, 
the mind cannot be subdued. Unless the mind is subdued, salvation of the soul is not possible. One will drift in the ocean of the world for lives together. Subdue your mind by the practice of Surat Shabd Yoga. Adopt no other method. Again and again, I stress that except Shabd (Divine Sound) there is no other spiritual practice."
“A perfect Guru or Sant Sat Guru, is one who has access to all the planes higher than the one where the aspirant's spirit is located. He comes down from the highest plane, i.e., Radhasoami Region, and is free to go up to any higher plane at His own will and choice. The Guru enables the disciple also to go up to a higher plane and to stay there by infusing in him His own higher and pure spirituality. In other words, the Guru's influence is similar to the influence of the sun on the earth."
Babuji Maharaj