We in sanatan dharma have a significant role of our guru in our lives. Guru enlightens the darkness of life with knowledge and divinity of experiences. 

One has to approch towards the litral and real meaning of achrya first. Who is achrya? The answer is आचिनोति हि शास्रार्थं सम्यगाचरते स्वयम् । आचरयति तान् लोके आचार्यं तं विदुर्बुधा ॥॥ 
One who studies and interprets the shastra setting the essential principles and follows himself also the same; Also who makes the people follow it - he is known to be an achrya.

The principle setter from all pramaan (proofs) of Ved, Upanishad, Geeta and Bhagvat is our Achrya. Then another quality is that is himself follows the same. Vallabhachrya gives prescription of qualities of guru as “कृष्ण सेवा परं वीक्ष्य दंभादि रहितं नरम्। श्रीभागवतत्वज्ञं भजेज्जिज्ञासुरादरात्॥” guru should me involved supremly to serving ShriKrishna himself , He mustn’t have ego and must be the man knowing the tatva(elements) of bhagvat shastra.  So guru should be following Bhagvat dharma with pridelessness. 

Such a guru should me treated as god almighty himself is our principle derived from shastras.  Bhagvat  (6/9/29) says that “आचैर्यो ब्रह्मणो मूर्तिः” Achrya is almighty god himself.
“इह आचार्यवान् पुरुषो वेद तस्य तावदेषं चिरं यावन्न विमोक्ष्येऽथ सम्पत्स्य इति॥” chhandogyopanishad (6-14-2) says that In this loka(world) the one who have Achrya he only knows the supreme almighty; he only waits till the body exists - that is he surely gets Attached to supreme almighty.
“आचार्यादेव विद्या विदिता साधिष्ठं प्राप्तीति”  chhandogya upanishad says (4-9-3) the knowledge seeked from achrya only gives the final civilised sucess. Shri Krishna says to Uddhava “आचार्यं मां विजानीयात् नावमन्येत कर्हिचित्। न मर्त्य बुद्ध्याऽसूयेत सर्व देवमयो गुरुः॥” -  know your achrya myself, dont insult him , dont see him as common man, He is filled with all the divine devas.

Shwetashwatar Upanishad says that “यस्य देवे परा भक्तिर्यथा देवे तथा गुरौ। तस्यौते कथिता ह्यर्था प्रकाशन्ते महात्मनः॥॥” one who have the bhakti for god and same for Guru also, that great personality’s heart will be enlighten with knowledge of these upanishads.
Thus we should processfully take diksha of Sharan and samarpan from our guru. This the supreme principle rather than independently setting our own principles for dharma, shastra and spiritulism.

Pustimarg has the essence of this principle traditionally conveyed from upanishads regarding guru as prabhu himself. 

In pustimarg , we accept the incarnation of Agni mukha(mouth) of Almighty - i.e Anand Bhrmn himself as MahaPrabhuji ShriVallabhachrya. Its not only our faith but also prescribed previously before the incarnation of shrivallabh. Agnipuran says that “वल्लभो अग्निरूपः श्रीविठ्ठल पुरुषोत्तमः” - ShriVallabh is form of Agni mukha and ShriVitthal is purushottam shrikrishna himself. There are many such intuitions of shastras regarding birth of shrivallabh and vitthal. ShriVitthal himself specifies that “स्ववंशेस्थापिताशेषमहात्म्यः” ShriVallabhachrya established his own divine significane inside his own lineage. This principle is called BinduSrusti parampara. The guru parampara flows on as per linage and their qualities as prescribed by shrivallabh in TatvarthDeepNibandh. 

So in pustimarg we consider Guru as shriVallabh and utmost almighty himself.

 

ShriRanchhodlalji - the 16th decendent achrya follows the pronciples of shriVallabhachrya and ShriVitthalachrya  -  propogates this principle in minds and hearts of Vaishnavites.