Transliteration
jñāna yajñena cāpyanye yajanto mām-upāsate |
ekatvena pṛthaktvena bahudhā viśvato-mukham || 15 ||
Translation
With the sacrifice of wisdom others propitiate Me as the Universal form in the unified manner, in distinct manner and in manifold manner as well. --Shri Madhvaharya Alternate translation: ------------------------- Others, too, besides offering the sacrifice of wisdom, worship Me as One, who is characterised by diversity in various ways, and is multiform (in My Cosmic aspect). --Shri Ramanujacharya
Purport
This is undoubtedly one of the very important Shlokas of Shrimad Bhagvad. It addresses one of the biggest religious questions ever possible, monotheism versus polytheism. In fact, this shlokas proves the very debate of monotheism v/s polytheism as superficial. One of many is the difference in comprehending the vastness.
The glory of Bhagvan Shri Krishna, the God is infinite, He has thousands of attributes and unlimited forms. These facts are described many times in Shrimad Bhagvad Gita and related scriptures. In Ch10.Sh40 Bhagvan Shri Krishna says
“nanto 'sti mama divyanam
vibhutinam”: there is no end to my divine manifestation(forms).
In the start of this chapter Sh4. Bhagvan Shri Krishna said
maya tatam idam sarvam jagad avyakta-murtina
“By Me, in My unmanifested form, this entire universe is pervaded”
Yet in ch7.Sh7 Shri Krishan said
“Mayi sarvamidam pritam sutre manigana eva.”
“Everything existing is connected to Me like Pearls on a thread”
Entire universe is pervaded from the forms created from the potency of Bhagvan Shri Krishna If one takes the universal form of his, Shri Krishna is one. But if one takes some specific form of the attribute of Shri Krishna then he finds multitude. As Shri Ram, He appeared as a man of virtue who crosses his human limits. But in the form of Shri Krishna, he appeared as Yoga Purushottam displaying his divine powers. Yet as Narsimha, he appeared as a ferocious half lion-half human form. On the other hand, he appeared as a dwarf Vamana.
Some devotees like Shri Ram incarnation, some others like Shri Krishan, yet some other may find refuge in the Narasimha avatar. These are simply the difference of acquiring certain attributes of God and not making different God as others claims.
That is what has been explained in this Shloka. Bhagvan Shri Krishna in clear terms explains, some devotees who have an inclination towards Janana Yoga(Yoga of Knowledge) take the universal form of Shri Krishna and worship him through the defined process of yajna. This is the main method of Vedas,
Some other devotees take a particular form of Shri Krishna and worship him using different rituals, steadfast, chanting and other methods. These are the methods as described in Puranas and other Smriti texts.
Though many others also worship different deities who again the manifested forms of Shri Krishna and the immediate guardians of humans. Again this very fact is described at various places in Shrimad Bhagvad Gita
"In the beginning, the creator Brahma created being(including deities) with the Yajna(Sacrifice) and said "By Yajna(Sacrifice) you propagate and grow, let Yajna(Sacrifice) be your wish-fulfilling cow of plenty" -- Ch3:Sh10
"By this Yajna(religious sacrifice), you please demigods and then those demigods will nurture you. In this way, supporting each way, you shall obtain supreme good"-- Ch3:Sh11
The essence of the fact is that variation of worship methods, what form or attribute of God one wants to worship does not make any difference in final returns till it is genuine and honest, as Shri Krishna said very clear, all paths ultimately lead to Him only
"All, who in whatever way worship me, I reward them accordingly as all men ultimately follow my path in all respects, O son of parth (Arjuna)."—Ch4:Sh11