Divine Power of Mantras:

Rama symbolized Rig Veda. He was Mantraswarupa (embodiment of mantras).
Lakshmana was Mantradrasta (one who contemplated on the mantras) and he put the teachings of Rama into practice. He followed Rama faithfully. He considered Rama Nama (repeating Rama's name) as the taraka (liberating) mantra. He, in fact, considered Rama everything --mother, father, Guru and God.
Bharata was the embodiment of Sama Veda and chanted Rama Nama incessantly with bhava, raga, and tala (feeling, melody, and rhythm). While Bharata was engaged in nirguna worship (worship of formless God), Lakshmana rejoiced in saguna worship (worship of God with form).
Atharva Veda manifested itself as Satrughna, who followed his three elder brothers and conquered not only the secular world but achieved victory over the kingdom of senses also.
The Vedas thus incarnated in the Treta Yuga (era) to impart a most precious message to mankind. The two great sages Vasishtha and Viswamitra declared to the world that the four Vedas had taken birth in human form as Rama, Lakshmana, Bharata, and Satrughna. As a consequence of great merit earned by Dasaratha, the four Vedas incarnated as his sons. If anyone asked Sage Viswamitra any questions about the Vedas, he replied, "All the four Vedas have incarnated as the four sons of Dasaratha to set an ideal to the world." Hence the Vedas are not formless; they have a form.
The mantras contained in the Vedas are of immense significance. When Sage Viswamitra realized that the rakshasas (demons) wanted to stop the chanting of Vedic mantras and destroy righteousness and truth on earth, he sought the help of Rama and Lakshmana, who symbolized the divine forces that descended on earth to destroy the demonic forces and establish peace in the world. With the power of mantras taught to them by Sage Viswamitra, Rama and Lakshmana annihilated the Rakshasas. This incident signifies the fact that with the power of Vedic mantras man can destroy his demonic qualities. By engaging themselves in the chanting of the mantras, the people of Treta Yuga annihilated their demonic qualities.
Symbolizing the divine powers of the Vedas, Rama, Lakshmana, Bharata, and Satrughna destroyed demonic forces and fostered divine forces in the world. The four brothers thus established the supremacy of the Vedas as manifestation of the aspect of God with form.
Each mantra has a form. It has also its own inner significance. When chanting is done with contemplation on form, it leads one to the path of self-realisation. The Vedic seers declared, "Vedahametam Purusham Mahantam Aditya Varnam Tamasah Parastat (I have seen the Divine Being who shines with the splendour of a billion suns beyond the realm of darkness)." The seers and sages transcended the darkness of ignorance and visualized the effulgence of the Divine. They chanted the mantras, contemplated on the form of the Divine, performed yajnas (sacrifices and rituals) and attained peace and bliss. They made use of mantra, tantra, and yantra in the performance of yajnas, which ensured peace and prosperity of the people in Treta Yuga. With the help of the mantras, they quelled the rakshasas (demons) and established the reign of gods.

Namasmarana for Man's Liberation
But the people of the Kali Yuga (the present age) have forgotten these mantras with the result that Kali Yuga has verily become Kalaha Yuga (the Age of discord and conflict). Even brothers quarrel with each other. They live and eat together in the same family, yet there is hatred and conflict between them.
Different means for man's liberation have been prescribed for each of the four Yugas. While meditation is prescribed as the primary means of liberation in the Sathya Yuga, performance of yajnas and chanting of mantras forms the means of liberation in the Treta Yuga. Similarly, archana (worship of God) is the chief means of liberation in Dwapara Yuga. But it is namasmarana (repetition of the name of the Lord) that is the main means of man's liberation in Kali Yuga. Since the people of Kali Yuga do not have the strength and capability to carry out rigorous sadhana (spiritual practices), they have been advised to do namasmarana.
Harernama Harernama Harernamaiva Kevalam;
Kalau Nastyeva Nastyeva Nastyeva Gatiranyatha.
In Kali Yuga, there is no other means more effective than the chanting of Divine Name for man's liberation.
The Ramayana is not an ordinary story. It contains the direct message of the Vedas. Rama symbolizes the wisdom of the Vedas. Rama married Sita, who represents Brahma Gyan (knowledge of Brahman). When Sita is taken away by demonic forces, Rama and Lakshmana search for her desperately.
The Ramayana contains thousands of slokas (verses). Since it was not possible to remember all the slokas of the Ramayana, the sages recommended the chanting of the Name of Rama. When the disciples of Vasishtha asked him what Divine Name to chant, the sage said, "It is enough if you chant the name 'Rama'. The Name of Rama will make you free from raga (attachment) and roga (disease)."
As I often tell the students, the name Rama has two syllables, Ra and ma. These two powerful syllables are derived from the names of Vishnu and Siva. The syllable, Ra comes from the ashtakshari (eight syllabled) mantra Om Namo Narayanaya. It is the life-breath of the ashtakshari mantra. Similarly, ma is the very soul of the panchakshari (five lettered) mantra Om Namah Sivaya.
The ashtakshari mantra Om Namo Narayanaya and the panchakshari mantra Om Namah Sivaya become meaningless when ra and ma are respectively removed from the words of these mantras. Without ra, the ashtakshari mantra becomes Om Namo Nayana, which is meaningless. In the same way, the panchakshari mantra without ma becomes Om Nah Sivaya, which is inauspicious. The Name Rama is the life-breath of both the Vaisanavites and Saivites (worshippers of Vishnu and Siva).
In the Treta Yuga, when the sages and seers were engaged in the chanting of the Divine Name of Rama, Ravana, Kumbhakarna, and other demons tried to put hurdles in their way. They thought that if they abducted Sita, who symbolized Brahma Jnana (knowledge of Brahma), Rama would lose His power. The Name would lose its potency without Jnana, just like sugarcane loses its sweetness without Rasa. Hanuman resolved to bring this rasa back to Rama and rejoiced in drinking Ramarasa (ambrosia of Rama's Name).
The people of the Treta and Dwapara Yugas considered the Name Rama to be the essence of all sweetness and enjoyed its nectarine taste. Instead of tasting the delicious spiritual sweetness of the Name of Rama, people today devour worldly sweets and expose themselves to the risk of becoming diabetic patients. Worldly sweets cause diseases, whereas the delicious sweet of Rama Nama rids one of all diseases. In ancient India, even the cowherds and shepherds chanted the Divine Name while tending their cattle and sheep. There were not many diseases in ancient times. Rama, Lakshmana, Bharata, and Satrughna propagated the glorious power of Vedic mantras to free the world from diseases and suffering.