What was the Orthodox Church's role in Russian expansion?

Question

Yuri Semyonov's The Conquest of Siberia says the main motivation for the Russian empire's eastwards expansion was the acquisition of furs (in the form of yasak, the fur tax assessed on native male subjects). Geopolitics was a relatively minor concern; no other power was rapidly expanding towards Russian territory, and the imperial military was in any case often occupied with wars in Europe.

Of course, the empire also had a state religion: the Orthodox church, which midway through the era of expansion, suffered a schism. Did it provide doctrinal justification for the conquest? Could it afford to missionize the new territory? Did the creation of Siberian dioceses such as the bishopric of Irkutsk change church politics?

Answer 1

Disclaimer: it is rather a long comment than an answer.

You have to keep in mind that a significant (if not predominant) part of Siberia colonists were Dissidents (раскольники, Schismatics). The crowd which settled in Siberia before 1666 stuck to the Old Ritual, and after the Schism the Dissidents moved there lets say more eagerly than Nikonians.

For a while the Crown looked away, because it was a win-win situation; of course Dissidents didn't want to draw too much attention by proselytizing locals.

In due time the State have had to assert the principality of the official canon. This remained the main theme of the Church policies in Siberia. Nobody paid too much attention to locals; they stayed Buddhist, Shamanists and to lesser extent Muslims until (and through) Soviet times.

Answer 2

The Tsar that started the expansion into Siberia was Ivan IV (the Terrible). While he was a fairly pious man, these conquests were at first simply wars against the fragments of the Mongol hordes that plagued Russia for centuries. The land seized from these hordes was given to private citizens for development, and it was them that hired the cossacks to subdue native tribes.