Here is a brief summary of the demographic analysis from the note:

#1 Tamil Nadu is second only to Kerala in terms of Christian population. In 2011, there were 44 lakh Christians in Tamil Nadu and 61 lakh in Kerala. These two southernmost states of India thus accommodate more than a crore of the total 2.8 crore Christians in the country.

#2 The share of Christians in the total population Tamil Nadu is 6.1 percent, which is also the second highest among the large states of India, though the proportion of Christians is higher in some of the smaller states and union territories, including some in the Northeast.

#3 The share of Christians in the Tamil Nadu population has been growing since 1951, when it was at 4.7 percent

#4 Christians in Tamil Nadu are concentrated in several pockets spread across the state. These include a pocket around Chennai city in the north; another comprising parts of Thanjavur, Tiruchirappalli and Dindigul in the middle; the Nilgiris and parts of Coimbatore in the west; Sivaganga and Ramanathapuram in the southeast; and, Tirunelveli, Thoothukkudi and Kanyakumari in the south.

#5 Of the pockets of high Christian concentration, the most intense is that around Kanyakumari. Christian numbers in Kanyakumari district have grown steadily for several decades and increased by more than 16 percentage points between 1921 and 2001. Christians now form a near majority in the district with a share of 46.9 percent.

#6 The northern pocket around Chennai city has also been witnessing considerable growth of Christians. In the composite Chengalpattu district, which has been divided into the two districts of Thiruvallur and Kancheepuram that surround Chennai, the share of Christians has risen from 2.2 percent in 1951 to 6.4 percent. Chengalpattu saw major spurts in its Christian population during 1961-71 and 1991-2001.

#7 The number and share of Muslims in Tamil Nadu is nearly equal to that of Christians. They have their pockets of high concentration in the eastern coastal taluks of Ramanathapuram and Pudukkottai; in some western taluks of Tirunelveli bordering Kerala; in Vellore in the north; and in the Nilgiris in the west.

#8 In the Ramanathapuram taluk of Ramanathapuram, Manamelkudi taluk of Pudukkottai, Shenkottai of Tirunelveli and Gudalur of the Nilgiris, the share of Muslims is between 25 and 28 percent and it is about 22 percent in Ambur of Vellore district.

#9 Overall growth in the share of Muslims in Tamil Nadu since 1951 has been less than that of Christians. But, there has been a visible spurt in the Muslim growth during 2001-11.

#10 The presence of Christians and Muslims in Tamil Nadu, like in Kerala, has historical antecedents. But, much of the growth in their presence in Tamil Nadu, as also in Kerala, seems to have occurred during the British period and in the period of Independent India.

Read the complete analysis here on the CPS blog.