Eastern Ukraine
According to a 2016 survey of religion in Ukraine held by the Razumkov Center, 73.5% of the population in Eastern Ukraine were Christians (63.2% Eastern Orthodox, 8.1% simply Christians, 1.0% Protestants, and 0.3% Latin Rite Catholics), 0.5% were Muslims, 0.3% were Jewish, and 0.3% were Hindus. Not religious and other believers not identifying with any of the listed major religious institutions constituted about 24.7% of the population. It also showed that approximately 55.6% of the population of eastern Ukraine (which in Razumkov's mapping excluded Donbass and consisted of the regions immediately to the west of it) declared to be believers, while 13.4% declared to be undecided or non-believers, and 3.5% declared to be atheist. 
A 2007 survey by the Razumkov Centre asked "Would you like to have your region separated from Ukraine and joined another state?" In eastern Ukraine, 77.9% of respondents disagreed, 10.4% agreed, and the rest were undecided. 
In a poll conducted by the Kyiv International Institute of Sociology in the first half of February 2014, 25.8% of those polled in East Ukraine believed "Ukraine and Russia must unite into a single state", nationwide this percentage was 12.5%.
History of Christianity in Ukraine
In 1988 with the millennium anniversary of the baptism of Rus, there was yet another shift in the Soviet attitude towards religion, coinciding with the Perestroika and Glasnost programmes. The Soviet Government publicly apologized for oppression of religion and promised to return all property to the rightful owners. As a result, thousands of closed religious buildings in all areas of the USSR were returned to their original owners. In Ukraine this was the then ROC's Ukrainian Exarchate, which took place in the central, eastern and southern Ukraine. In the former-uniate areas of western Ukraine things were more turbulent. As UGCC survived in diaspora and in the underground they took their chance and were immediately revived in Ukraine, where in the wake of general liberalization of the Soviet policies in the late-1980s also prompted the activization of Ukrainian national political movements. The Russian Orthodox Church became viewed by some as an attribute of Soviet domination, and bitter, often violent clashes over church buildings followed with the ROC slowly losing its parishes to the UGCC.