In the Vedic period the principal ritual was the yajna, although in later times it evolved into pUja. This seems to indicate a Tantric influence according to Georg Feuerstein (see his book on Tantra), and I think this is very plausible. So what is the relevance of ritual pUja in our time, especially for sAdhakas in quest of the true nature of the self?
The span of human life, ideally 100 years in the Vedic framework, is divided into four Ashramas or stages of about 25 years each:
brahmacarya: childhood and youth during which celibacy is practiced and the VedAs and VedAngas are studied
gRhastha: the stage of being a householder and raising a family, when ritual yajna is practiced
vAnaprastha: the stage of moving to the forest dwellings once the children have grown and left the home
sannyAsa: the stage of a renunciate
The ritual yajna, which is part of the karmakANDa portion of the Veda, was primarily intended for the practice of householders. This is the stage where a human desires practical gains in the world, and therefore propitiates the gods for the attainment of these practical ends. The pursuit of BrahmavidyA (knowledge of Brahman) was intended for all stages, but its emphasis changes with the human seasons. In the brahmacarya stage the student learns all the scriptural knowledge that will be needed throughout life. Rituals including pUja and yajna are important insofar as being of practical value to believing householders. They also support priests and temples that serve to sustain and transmit some aspects of Vedic culture to the next generation. Once the practical means to raise and support a family have been obtained and the gRhastha stage is completed, it was intended that from the vAnaprastha stage onward the emphasis would shift away from ritual to meditation. At any stage the ritual worship was not meant to be a substitute for the practice of meditation to attain Gnosis of Brahman.
These points are useful for the sAdhaka to bear in mind as the ritual aspects are integrated and evolved into sAdhanA. For instance, the celebration of annual festival days is useful for social and cultural reasons and can serve to evoke devotion for a particular deity in the aspirant. However, the practice is too infrequent to be of value as a sAdhanA. Observances on special days of the lunar fortnight (amAvashya, paurNami, ekAdhashi) can also be useful, especially once the aspirant has gained awareness of cyclical influences on the physical, energetic and mental sheaths. While these serve to reinforce the regularity of habit in the conscious mind of the aspirant, any ritual that is not performed daily does not have the regularity to qualify as true sAdhanA.
Apart from regularity, the other requirement of sAdhanA is intensity. When rituals are performed without knowledge of the meaning of the mantras or shlokas, the efficacy is considerably lessened. Although it is true that mantras can be very powerful, and do represent manifestations of Consciousness, their power depends on the strength endowed to them by the consciousness of the person reciting them. Therefore, the same mantra does not have its full potency when recited without knowledge of its meaning. The purpose of reciting the mantra and knowing its meaning is to evoke a 'bhAva', or mental attitude. As this 'bhAva' is reinforced, the aspirant will gradually turn from reciting longer mantras that form pUja practice to shorter mantras that are recited mentally as 'japa'. So there is a natural progression from ritual to 'japa' and meditation along the spiritual path. If the steps towards this progress are not followed, the result is stasis on the spiritual path.
In the article on the Northern and Southern paths it was already discussed that the Southern path is not liberating. While ritual worship may count as one of the good deeds that earn puNyam (merit), they do not lead to liberation. Especially in Kali Yuga the power of ritual is considered to be relatively diminished. We live in a world that is aged. By Vedic reckoning this jagat is in its fourth quarter of existence. Just as a human being (microcosm) in the fourth quarter of life does not find much efficacy and benefit through ritual, so is the case for the Macrocosm.
Therefore, it is useful for the sAdhaka to adopt a tolerant attitude towards ritual worship, but to not squander energy and focus on them. As one's individual relation to the Truth deepens through progress on the path, it is natural to find less value in the exoteric aspects that serve social and cultural needs. If stasis in ritual aspects is avoided, then this progression from the exoteric to the esoteric aspect results in a sAdhanA that leads to spiritual insights.