Answer
You do not understand the mood of saṅkīrtana unless you hear the Bhagavad-gita and Srimad-Bhagavatam.
Simply singing is not saṅkīrtana. A player can sing, and people may ritualistically sing together, but saṅkīrtana means jointly glorifying the Lord. It does not only mean mṛdaṅga and karatālas. A Bhagavatam class is also saṅkīrtana.
Therefore, do not understand saṅkīrtana only in the colloquial sense. Understand its philosophical meaning.
Srila Prabhupada even used the word saṅkīrtana for book distribution. He would ask, "Why have you not gone out for saṅkīrtana?" Therefore, book distribution is also saṅkīrtana.
As for why Sri Chaitanya Mahaprabhu established worship in a particular way, you cannot fully answer that question. One would require infinite intelligence to understand the infinite reasons behind the Lord's actions. Speculating about them will not help.
Instead, simply follow what He instructed:
Perform saṅkīrtana.
Worship the Deities.
Perform mṛdaṅga and karatāla saṅkīrtana.
Distribute books.
All these are forms of worship of Krishna's two-handed form.
Why is it worship of Krishna's two-handed form? Because, according to your qualification, Krishna accepts your worship in that particular mood.
Ultimately, one may not even attain Goloka Vrindavan. One may attain Vaikuntha.
Only because of Srila Prabhupada, who is a pure devotee, can his followers be elevated to the Supreme Lord.
Please understand this carefully.
Although we worship Radha-Krishna, we worship Them in the mood of Lakshmi-Narayana. Within Radha-Krishna, Lakshmi-Narayana is included. We are worshipping Krishna's two-handed form, but in the mood of Narayana.
Srila Prabhupada could have said that we are not qualified to worship Radha-Krishna and therefore installed only the four-handed forms of Lakshmi-Narayana. He did not do that.
He installed Radha-Krishna because They are our ultimate goal. He also explained that within Radha-Krishna all other forms are included, including reverential Lakshmi-Narayana worship.
Therefore, worship in this way, and gradually, one day, you will realize the proper mood.
Similarly, we chant the Hare Krishna maha-mantra.
The ultimate mood of chanting the holy name is to glorify and celebrate the intimate pastimes of Radha and Krishna.
However, what did Srila Prabhupada teach us to pray?
He taught us to pray, "Please engage me in Your service."
As conditioned souls and neophyte devotees, when we chant the Hare Krishna maha-mantra, we are not praying, "Please engage me in service in Goloka Vrindavan as an assistant of the gopis." Srila Prabhupada said such meditation is premature.
That stage will come one day.
At present, we are not even able to engage our senses fully in the service of Narayana while still identifying with the body. Therefore, such meditation would simply be imitation.
Our first stage is to realize, "I am spirit. I am not this body."
If you honestly recognize your present position without cheating yourself, Krishna is very pleased, and He will give you the realization you need.
Without being situated on the Brahman platform, one cannot perform pure devotional service.
Therefore, all of us are presently engaged in mixed devotional service.
We should always remain honest about our actual spiritual standing.
According to our qualification, we worship the one Supreme Lord. Understanding this oneness is very important.
At our present stage, we should not become absorbed in making fine distinctions. Those finer differences exist, but we are not yet qualified to appreciate them fully.
Mahaprabhu taught that Narayana comes from Krishna. So why should we argue?
Such arguments are a waste of time.
Let others remain where they are, and let us remain where we are according to our parampara.
That is not wrong because, ultimately, they are all one.
Krishna also explains that, in the material world, all incarnations appear through Narayana.
Therefore, when Krishna appeared before Devaki, He first manifested His four-handed form. That is the rule—every incarnation comes through Narayana.
Suppose someone passes through several rooms before entering through the final door. You may say that he came through that last room, but he actually originated much farther back.
Similarly, Krishna comes from Goloka Vrindavan, although He manifests through Narayana.
This confidential knowledge was revealed by Sri Chaitanya Mahaprabhu. Such revelations are made according to the Lord's arrangement and at the appropriate time.
In that sense, it is also correct for others to say that Narayana first appeared before Devaki and then Krishna manifested His two-handed baby form.
From our acaryas, however, we receive this deeper understanding.
