We as Buddhists consider "Dhamma / Dharma" to be holy.But do we know the reasons that make it holy?
Bodhidharma is the legendary founder of Zen in China. He is said to have arrived in China about 520 CE. (Buddhism had by then been known in China for about 400 years.) He was soon summoned to the emperor, who had questions for him.
"I have endowed hundreds of temples and monasteries, and endorsed the ordination of thousands of monks and nuns; what is my merit?" -- the emperor asked.
Bodhidharma, usually depicted as a scowling, hooded, bearded figure, shot back: "There is no merit."
"What then is the main principle of the Holy Teaching?" the emperor asked.
"Open, empty, nothing holy!" (廓然無聖) replied Bodhidharma.
In India there are many practices aimed towards liberation from the satisfactoriness of Dhamma. Hence the Buddha used this model where the Dhamma is revered and forms a "religion" like institution around it.
In addition, if the teaching is not revered people will not learn it and practice it. Also it will not attract others. It is very rarely you get to know that the reality is in the form of a teaching hence you should have respect to the teaching.
Hence the reverence to the Dhamma.
Also the Buddha has asked to treat the Teaching like a Boat to get to the other shore and not carry it with you.
Lord Buddha advised a form of meditation and worshiping that focus on the holiness of Dhamma / Dharma. It is called "Dhamma Anussathii".These are the reasons that makes Dhamma / Dharma holy.
Swakkhatha - Lord Buddha taught Buddhism inn the best way/ in the best manner possible
Dhamma/Teachings of Lord Buddha has been presented by Lord Buddha in the best manner possible and therefore can't be explained in any better way above lord Buddha's teachings.
Sandhittika - Dhamma/Dharma can be realized in this life itself
Dhamma is not incapable,anyone can understand and realize it in this life and therefore there is no need to postpone the path.
Akalika - Dhamma/Dharma can be understood and realized in any time. In present and in future.Just like how the great ones did in the past.
Dhamma/Dharma is timeless, so there is no need to modify,upgrade or modernize it.Just like the past it is still equally effective today and in future.
Ehipassika - Dhamma/Dharma has no secrets or hidden paths/teachings, Therefore anyone can be invited in to come and see for themselves.
Dhamma/Dharma itself is fully open and contains no hidden paths or teachings.As Dhamma/Dharma contains no secret there is nothing to mask or hide.So anyone can enter and learn or inspect Dhamma/Dharma.
Opanaika - Dhamma/Dharma can only be understood from the inside,by yourself.Thw ewalization can't be given,one must find it within.
No one can give you the realization or nirvana you must find it yourself.
Pachchaththan wedithabbo vinyohithi - Dhamma/Dharma must be understood by wise ones in their own capacity or potential
Only the wise will understand Dhamma/Dharma in their own capacity.The ones who are not wise may not.