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%.
Ukrainian Greek Catholic Church
The clergy who joined the Russian Orthodox Church were spared the large-scale persecution of religion that occurred elsewhere in the country (see Religion in the Soviet Union). In the city of Lviv, only one church was closed (at a time when many cities in the rest of Ukraine did not have a working church). Moreover, the western dioceses of Lviv-Ternopil and Ivano-Frankivsk were the largest in the USSR and contained the majority of the Russian Orthodox Church's cloisters (particularly convents, of which there were seven in Ukrainian SSR but none in Russia). Orthodox canon law was also relaxed on the clergy allowing them to shave beards (a practice uncommon to Orthodoxy) and conduct liturgy in Ukrainian as opposed to Church Slavonic.