Here is a brief summary of the CSP findings from the note:

#1 The number and share of Christians in undivided Andhra Pradesh, as also in both the Andhra and Telangana components, had been rising steadily up to 1971.

#2 Their number in undivided Andhra Pradesh was 3.6 lakh in 1911, it rose to 18.2 lakh in 1971; and their share in the population rose from 1.68 to 4.19 percent.

#3 Of the 18.2 lakh Christians in 1971, 14.9 lakh were in the Andhra component of the state, where they formed 5.4 percent of the population. Only 3.4 lakh were in the Telangana part, where they had a much lower share of 2.1 percent.

#4 After 1971, there was a sudden and steep decline in the population of Christians in the whole of Andhra Pradesh, but especially in the Andhra component.

#5 Between 1971 and 2011, the number of Christians in this component has declined by more than half, from 14.9 to 6.8 lakh and their share in the population has declined from 5.37 to 1.38 percent.

#6 Within the Andhra component, the Christians are concentrated in the central coastal districts of West Godavari, Krishna, Guntur and Prakasam and to a lesser extent in the neighbouring Rayalaseema districts of Kurnool and Kadapa. Of 14.9 lakh Christians in the Andhra Pradesh component in 1971, about 10 lakh were in the first four of these districts and another 2 lakh were in Kurnool and Kadapa.

#7 Share of Christians in this region had reached very high levels in 1971, when they had a share of 14.6 percent in the population of Guntur and 10.8 percent in that of Krishna.

#8 The decline in Christianity seen in Andhra Pradesh after 1971 is mainly because of the near collapse of Christian population in this region comprising West Godavari, Krishna, Guntur, Prakasam, Kurnool and Kadapa districts. In these six, their total population has declined from 12.0 to 4.2 lakh between 1971 and 2011.

#9 The greatest decline of Christians has occurred in Guntur and Prakasam districts. Their number in the former has declined from 4.2 lakh to less than 90 thousand and their share has dropped from 14.8 to 1.8 percent. In Prakasam, the number of Christians has come down from 1.35 lakh to less than 19 thousand and their share from 7.0 to 0.5 percent.

#10 Christianity in this region was not a new or recent phenomenon in 1971. There was considerable Christian presence here already in 1911. Christians then had a share of 7.3 percent in the population of Guntur; and it grew to 14.8 percent in 1971.

#11 The sudden decline of Christianity after 1971 in this region is therefore a significant phenomenon that needs to be understood.

#12 This decline in the share of Christians in Andhra Pradesh as a whole, and particularly in the central coastal districts of Andhra and a couple of neighbouring districts of Rayalaseema, after 1971 is matched by a corresponding rise in the share of Scheduled Castes. The correspondence is uncannily exact in the average for the whole undivided State and in many individual districts.

#13 The decline is almost entirely in the rural Christians. The number of urban Christians has in fact increased since 1971, and the increase in Hyderabad district is substantial. This is another indication that the decline in Christianity is associated with the converts from the Scheduled Castes who are predominantly rural.

#14 Available data strongly suggests that after 1971 a large number of converts to Christianity form the Scheduled Castes have chosen to be counted among the Scheduled Castes rather than the Christians.

#15 This decision is perhaps motivated by the fact that the privileges associated with that caste status are not available to those who convert to Christianity. It is remarkable that while the number of Christians was steeply declining in Andhra Pradesh, there was a significant increase of the Christian numbers among the Scheduled Tribes, who do not lose their privileges on conversion.

#16 It is important to know whether the decision of the converts from the Scheduled Castes to be counted as non-Christians amounts to a withdrawal from Christianity or merely hiding of the fact from the Census and secular authorities. But this question cannot be answered on the basis of the Census data alone.

#17 This large decline in the number of Christians in a relatively small region, where Christianity had taken roots several decades ago, is a phenomenon that needs to be studied in detail at the micro-level to determine its nature and its causes.

#18 The phenomenon strongly suggests that there may be large numbers of hidden or lapsed Christians in other parts of the country also. International scholars associated with the Church generally estimate the number of Christians in India to be much higher than the numbers counted in the Censuses. A study of the phenomenon of the sudden decline of Christians in Andhra Pradesh would help in clarifying this mismatch between the Census numbers on Christians and the international estimates.

Read the CSP note here for detailed analysis.