Sweden, "the wildest and most remote of the Scandinavian lands," was the last Scandinavian region to be converted. The specifics of its conversion remain as remote and mysterious to historians as the land's medieval reputation.

The earliest attempts were seeming failures. Ansgar, the famous apostle to Denmark, attempted to establish a Christian outpost as early as 830, building a church in the town of Birka. But Swedes showed little interest and, when Ansgar died, so apparently did the Christian presence.

We know of a second Frankish missionary who was soon forced to flee the land, and a century after Ansgar's attempt, the archbishop of Hamburg undertook a new mission—with as little success as Ansgar.

In western Sweden, things weren't much better. One ruler, Erik the Victorious, converted—probably to marry the daughter of a Polish duke, a devout Catholic. But Erik quickly lapsed and died a pagan around 995.

When success did come, it came haltingly. Erik's son Olof (995-1022) publicly identified himself as a Christian: in one town he struck coins with Christian slogans (such as "God's Sigtuna"), and he founded a bishopric at Skara. His son Anund (c. 1022-c.1039) became the first member of the family to take on a Christian name: James. Contemporary historian Adam of Bremen called him the "most Christian king of the Swedes," and claimed that while he reigned, Christianity was "widely diffused" in Sweden.

Not quite—unless he meant that Christians, still a small minority, could be found in many areas of Sweden. Missionaries from England and Denmark were having limited success in towns and country. But when they tried to force the issue, they ran into stiff opposition. When an English missionary smashed an image of Thor to demonstrate the power of Christ, he was instantly killed.

In the Uppsala region, even though it was ruled by King Stenkil—a Christian—paganism stubbornly held its ground. The local capital of paganism was the temple in Uppsala, which Adam of Bremen described: "It is situated on level ground, surrounded by mountains. A large tree with spreading branches stands near the temple. There is also a spring nearby where the heathens make human sacrifices. A golden chain completely surrounds the temple, and its roof, too, is covered with gold."

The temple housed three gods—Thor flanked by Odin and Frey—to which priests offered sacrifices. Every nine years, a major ceremony was held, with people from all the Swedish provinces bringing sacrifices. According to Adam, "the most distressing feature of this festival is that Christians too participate in the sacrifices . …Animals and humans alike are sacrificed,and their bodies are hung in the trees of a sacred grove that is adjacent to the temple."

About 1060 King Stenkil made Adalward ("the younger") bishop at Sigtuna. Adalward, an enthusiastic evangelist, traveled about the countryside smashing idols and winning many converts. But when he and another bishop concocted a plan to finish off the opposition by burning down the great pagan temple at Uppsala, Stenkil dissuaded them, feeling that the pagan backlash would hurt the Christian cause (see "The Limits of Power Evangelism," page 33).

Stenkil's judgment appears to have been correct. A few years later (1080), when his successor King Inge I tried to forcibly end the pagan cult at Uppsala, he was promptly expelled and replaced by his brother-in-law,Sweyn. Though a Christian, Sweyn agreed to permit pagan worship (and thus earned the nickname, "the sacrificer"). It wasn't until Inge gathered an army, defeated Sweyn, and imposed Christianity in the region that public pagan rituals at Uppsala ended (in about 1110—though they continued privately for generations.

For many decades, if not centuries, such syncretism prevailed. Polytheism was not adverse to permitting another god into its pantheon. Pagan Vikings had sent offerings of thanks to Saint Germain near Paris and to Saint Patrickin Ireland for successful raids. Before one important battle, a Swedish Viking army in Courland cast lots and determined that Christ was the god who would help. When they won, they gave thanks by fasting for 47 days in Christ's name—with no thought of converting.

In many instances, though, the pagan past made possible the Christian future. One story goes that in Gotland (an island off of eastern Sweden), Botair of Akubekk built a Christian church. When pagans burned it down, he built a second, under a cliff by the shore where pagans sacrificed to their gods. When pagans threatened to burn it as well, Botair locked himself inside and said, "If you burn it down, you shall burn me with it." His father-in-law joined him, adding, "Do not burn down the church. It stands on sacred ground." The father-in-law's reasoning seems to have won the day: the church remained intact.

Certainly church politics played a role in Sweden's conversion (in 1164 Uppsala was named an archbishopric), as did key martyrdoms (in 1160, Erik IX was killed by rebelling nobles and his shrine flourished). But overall, only through many failures and by much perseverance, sustained over many generations, did "wild and remote" Sweden submit to Christ.

Mark Galli is editor of Christian History.