Answer
Worship of the Lord is performed in many ways, and people worship for many reasons. Once these reasons are understood, the question of whether incense, lamps, camphor, and the like are necessary resolves itself.
1) Worship performed out of tradition: What is seen in the home and family — visiting the temple, lighting lamps and incense, performing aarti — children imitate the same. There is usually no awareness of the purpose; the tradition simply continues. Many priests too, lacking deep study of the scriptures, guide others based on tradition rather than knowledge.
2) Worship performed for mental peace or to remove fear: Many people are inwardly beset by anxieties. They feel that lighting a lamp or incense will please God, remove misfortune, and improve their fate. With such a sentiment, they light lamps at home or in the temple.
3) Worship arising simply from a desire to connect with God: Some people worship neither to avert misfortune nor merely out of tradition. They worship because they feel that one must do something to connect with God. Lighting a lamp or incense sticks feels natural to them. This sentiment is sacred, even if it is still at a preliminary stage.
4) Seekers who, having received proper guidance, progress toward moksha: Some people — who receive true scriptural knowledge and proper guidance — consider the ultimate goal of life to be liberation from suffering and attainment of moksha. They aspire to the eternal bliss of the Lord's abode. For such seekers, lamps and incense are neither required nor compulsory. They follow whichever path the Gita prescribes — karma-yoga, jnana-yoga, bhakti-yoga, japa-yoga, or sharanagati-yoga.
So, are lamps and incense necessary? The answer is simple:
If done with devotion, lighting a small lamp or incense is fine; and not lighting them is equally appropriate. Why? Because there is no mandatory injunction for them in the principal scriptures, and God's grace does not center on external objects — it centers on inner feeling and spiritual knowledge.
The Vedic perspective: In Vedic literature, lamps and incense are not considered essential. There, fire-centered yajna is prominent, in which offerings are made into the sacred fire. However, the Bhagavad Gita says: "The yajna of knowledge is superior to all material yajnas." (4.33)
The Lord describes the study of scripture — listening, reading, understanding, and applying it in life — as the yajna of knowledge. From this perspective:
If you study the Bhagavad Gita, Ramcharit, or Bhagavat Purana, that itself is jnana-yajna — far superior to lamps and incense.
If you still wish to create a sacred atmosphere, you may light one or two incense sticks, but avoid lighting oil lamps every day.
From the standpoint of bhakti-yoga: The depth of devotion lies not in lamps and incense, but in the feeling. Yet in the beginning, they can be helpful in awakening that feeling. Surrender, remembrance, meditation, charity, service, and chanting the name of the Lord — these are more dear to God. When the heart becomes pure, sometimes tears fill the eyes. Two such tears carry more spiritual power than two thousand lamps.
From the standpoint of karma-yoga and japa-yoga: In karma-yoga, no external aid is required. Performing every action as an offering to God — with desireless intent and without attachment — itself leads to liberation. In japa-yoga too, lamps and incense are not necessary. A single sincere, heartfelt utterance of "Rama" or "Krishna" is superior to lighting dozens of lamps.
Conclusion: For bhakti, jnana, or moksha — lamps and incense are not compulsory.
If you do use them in the beginning, keep a few things in mind: Since these are merely external aids, keep the use of lamps to a minimum (such as only during aarti), because there is a risk of accidents. Even in aarti, if camphor is used, it extinguishes after the aarti, thus eliminating the risk of an accident.
Continuous smoke blackens the walls, and oil is an expense. If the same money is spent in charity — feeding birds or helping someone in need — greater welfare results.
For fragrance, just two incense sticks are sufficient. Many people float lamps in rivers; if that same money were given to the poor, the merit would be far greater. Some Puranas have praised lamp-offering, but scriptures like the Gita do not encourage such rituals.
What does the Lord truly desire? A pure heart, faith, knowledge, love, remembrance, charity, service to others, and surrender.
If you regularly study the Gita, Bhagavat Purana, and Ramcharit, it will soon become clear that the path to God is illuminated not by external objects, but by inner feeling and spiritual knowledge. This does not mean that external symbols should be abandoned entirely; only that their use should be minimal. Hari Sharanam.