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%.
Russia
Traced back to the Christianization of Kievan Rus' in the 10th century, Russian Orthodoxy is the dominant religion in the country; smaller Christian denominations such as Catholics, Armenian Gregorians and various Protestant churches also exist. The Russian Orthodox Church was the country's state religion prior to the Revolution and remains the largest religious body in the country. An estimated 95% of the registered Orthodox parishes belong to the Russian Orthodox Church while there are a number of smaller Orthodox churches. However, the vast majority of Orthodox believers do not attend church on a regular basis. Easter is the most popular religious holiday in Russia, celebrated by a large segment of the Russian population, including large numbers of those who are non-religious. More than three-quarters of the Russian population celebrate Easter by making traditional Easter cakes, coloured eggs and paskha.