The Government argues or implies that Untouchability (or Dalit status) is essentially part of the Hindu religion and that it plays no part in the non-Hindu religions. So a Dalit who adopts a non-Hindu religion like Christianity ceases to be a Dalit. In other words, it is not possible to be a Christian and an untouchable at the same time.

This is false. That is not how it came about. Untouchability was based on race and not on religion. An untouchable was made an untouchable, not because he was outside of the Hindu religion but he was outside the Hindu race. Even if he adopted the Hindu religion, he did not thereby cease to be an untouchable. This created the possibility of a group of people who were both Hindu in religion and untouchable in status. If such a person now becomes Christian or Sikh or Buddhist, this change away from the Hindu religion still leaves him an untouchable in status because of his race.  The government has recognised  this fact in the case of the Sikhs and Buddhists, recognising that some people are Sikh and Dalit , or Buddhist and Dalit , at the same time , but illogically it refuses to use the same principle to recognise the possiblity of a people who are Christians and untouchables  at the same time, which is the same thing as refusing to include Dalit Christians into the list of the Scheduled castes, the list of Dalits.

There are many new converts to the Hindu religion in America and Europe, but the concept of caste and untouchability has not come to them with the new religion ,  for they are of the one white race.  The same obtains with those who have become Buddhists  in Japan , Korea and Taiwan.

Unfortunately, though dogmatically Christianity favors equal opportunity,  caste discrimination did not die out at the time of conversion from Hinduism but still prevails in most parts of the  country.

It may be argued that Sikh dalits or Buddhist dalits were given reservation because Sikhism and Buddhism are offshots of Hinduism.

This is false. If it were true, they should have been recognised for reservation rights in 1936 and 1950. In fact they got reservation rights much later, in 1956 and 1990, and that by political pressure. The Constitution speaks of Scheduled castes only in articles 330, 332, 334, 335, 338 and 341. Nowhere in those in six articles is there any mention of religion.

It may be argued that if the Dalit Christians are included in reservation, it will do harm to the Hindu dalits by cutting into the limited resources available.

This is false. Christian dalits form only a small percentage of the poplulation of India (1.4), and only 9.5 percent of the total  dalit population.  Similar inclusion was done for Sikh dalits in 1956 and for Buddhist dalits in 1990. At that time, no such economic objection was raised.