यो यो यां यां तनुं भक्तः श्रद्धयार्चितुमिच्छति | तस्य तस्याचलां श्रद्धां तामेव विदधाम्यहम् ||७-२१||
yo yo yāṃ yāṃ tanuṃ bhaktaḥ śraddhayārcitumicchati .
tasya tasyācalāṃ śraddhāṃ tāmeva vidadhāmyaham ||7-21||
Whatsoever form any devotee desires to worship with faith that (same) faith of his I make firm and unflinching.
In simple words
Krishna reveals his generosity: "Whatever form of the divine a person wants to worship with sincere faith — I am the one who makes that faith strong and steady in their heart."
7.21 यः who? यः who? याम् which? याम् which? तनुम् form? भक्तः devotee? श्रद्धया with faith? अर्चितुम् to worship? इच्छति desires? तस्य तस्य of him? अचलाम् unflinching? श्रद्धाम् faith? ताम् that? एव surely? विदधामि make? अहम् I.Commentary Tanu or body is used here in the sense of a Devata (god).The Lord? the indweller of all beings? makes the faith of that devotee who worships the lesser divinities? which is born of the Samskaras of his previous birth? steady and unswerving. (Cf.IV.11IX.22and23)
Contemporary scholarly and practical interpretations for modern seekers.
This interpretation draws on a specific tradition and may not represent the view of any single school. For authoritative guidance within a specific tradition, seek a qualified teacher.
Modern
In the opening portion of this chapter, the Blessed Lord Krishna has already made the distinction between the eternal Self and the material world—between consciousness and inert matter—and has described how all names and forms are woven within Him. Thereafter, He has also explained how human beings, deluded by the modifications born of the three-fold nature of maya, fail to recognize their own pure Self. Without the consciousness of the atman, the inert instruments of body, mind, and intellect cannot function of themselves.
It is observed in the world that all devotees do not worship the Divine in a single form. Each devotee endeavors to reach truth through the worship of their chosen deity. The Blessed Lord Krishna makes a clear declaration: whichever devotee worships the Divine with faith—in whatever form, in a temple, mosque, gurdwara, or church, in solitude or in public—I establish that very faith of theirs in their chosen deity. The true student who understands the essence of the Gita can never become rigid, sectarian, or intolerant. All the manifest forms of the Divine rest upon one supreme Truth, from which the plant of devotion in the devotee's heart receives the water of faith to flourish, bloom, and bear fruit—for the Lord Himself declares: I establish that faith.
When contemplated from a spiritual perspective, this verse reveals an even deeper meaning. Whatever subject a human being continuously reflects upon, they become firmly attached to and established in it. Through unbroken contemplation, the impressions of that subject become firm in the mind, and thereafter the person's desires and actions flow accordingly. Following this same principle, through constant reflection upon the atman, a human being can directly experience their own pure nature.
In essence, the Lord's teaching is this: as we think, so we become. Therefore, if one person has fallen prey to base qualities while another is endowed with divine qualities, both should be understood as the result of their differing thoughts. Thought is part of nature; the world takes shape according to thoughts, and all of this rests upon one foundation—the all-pervading atman. Through faith that continuously grows and flourishes, how does a human being attain the desired fruit?