Why: whatever form a devotee worships with faith, Krishna makes that very faith steady, again describing something like an underlying respect for however someone's genuine devotion is currently expressed, whatever its specific object.

In life: someone's specific practice or belief may look different from yours while still reflecting the same underlying sincerity and effort you'd recognize and respect in your own.

Teaching: extend genuine respect to someone else's differently expressed but sincerely held devotion or discipline, rather than assuming your particular form is the only legitimate one.