At the start of the Neolithic period around 4000 BC, farming was introduced to Norway by technology from southern Scandinavia and increased farming of oats, barley, pigs, cattle, sheep, goats, and more. Around this time, the Corded Ware culture in middle Europe began. During this period, neighboring kingdoms brought new weapons, tools, and the Indo-European language into Norway. The Indo-European language became the roots for the current Norwegian language. From here, Norway continued to grow and farm. By the Nordic Iron Age (500 BC-800 AD), Norwegians were beginning to trade with Rome and increase fortifications as people groups explored and moved north. Next, the famous Viking Age began, characterized by increased trade, colonization, and raids on nearby kingdoms. Conversion of Norway to Christianity began in 1000 AD because of raids on Christian kingdoms like Ireland, Britain, and Frankish kingdoms.
Prior to this, Norwegians followed a Nordic paganism likely adopted from nearby Western Germany. Vikings did not have official places of worship like Christians have churches. Rather, Nords worshiped in “sacred groves,” at home, or at a simple altar. Their religion was primarily based on ancestor-worship and a variety of deities. Deities commonly dwelled in objects of nature: trees, bodies of water, plants, and more.
All information from: Øyvind Stenersen and Ivar Libæk, The History of Norway. Lysaker: Forlaget Historie og Kultur, 2003.