When was the Christianization of Europe Complete?

In a different post, I talked about different ideas of what defines Europe, and whether it is a region or a continent. One idea I mentioned was what was historically called "Christendom", the contiguous area where Christianity was the dominant religion. That brought up the fact that Christendom's boundaries have changed dramatically, which brings up this question: When, if ever, was the area I defined as "Europe" completely dominated by Christianity, or which pagan group was the last to be Christianized in Europe?

There are interesting YouTube videos that show the progress of Christianity in Europe, including one by Ollie Bye. Christianity in Europe started in Greece and Rome, a fact anyone familiar with St. Paul would know. Generally, Christianity spread through various communities in the Roman Empire until the same empire that persecuted Christianity so heavily was itself converted to Christianity by the end of the 4th century. From there, Christianity spread northward by way of missionaries interacting with or confronting the Germanic tribes, who invaded the western Roman Empire, and the Slavic tribes, who invaded the northern Byzantine Empire.

By the time of the East-West Schism in 1054, there was just one large pagan region left, consisting of the Baltic countries, Finland, Karelia, and "Sapmi", the arctic homelands of the Sami people. The Northern Crusades finished off paganism in the Baltic countries during the 13th century, and Sweden just about Christianized Finland for the most part at the same time. This left only the Sami people. Southern Spain and southern Ukraine were Muslim at the time; the re-Christianization of Spain would be completed by 1500.

The Sami and Karelian peoples were interesting holdouts of paganism, indeed. When Columbus sailed the ocean blue, they were still pagan. When Luther broke from the Catholic Church, they were still pagan. That means parts of the Americas were Christianized before the Arctic region of Europe! This also means that the Sami and Karelian homelands never had a Catholic period, unlike most of Norway, Sweden, Denmark, and Iceland, which were Catholic countries from roughly 1000 to 1530, and Finland from roughly 1300 to 1530.

Another screenshot from Ollie Bye's video, showing how much of America was Christian before that last pagan holdout. Southern Ukraine, meanwhile, was still under Muslim control.

The Karelian and Sami peoples finally began to convert in the 17th and 18th centuries as Sweden and Russia closed in the gap between the two countries. It's still unclear to me when exactly the partition of Sami and Karelian lands was complete; perhaps the northern border between Sweden and Russia was undefined for a while. Either way, Sweden was zealously Lutheran by this time, and Russia was zealously Orthodox. Both countries were also expanding their borders and were rising great powers in the 17th century. It seems that by that century Karelians were more or less Orthodox, leaving the Sami people as the very last pagans of Europe. With Lutheranism as the official religion of Sweden, which also started to spread Lutheranism by the sword during the Thirty Years' War and afterward, Swedes began to get rid of any pagan objects they saw, such as the Sami shaman drums. The Swedish government seemed to prefer Christianization by force, though there were also Swedish missionaries who were more amiable. Finally, by the turn of the 1800s, Sami people were Lutheran and saw their pagan religion as a thing of the past.

Meanwhile, in southern Ukraine, the Crimean Khanate was in trouble. The 18th century saw Russia reach the summit of its power, having defeated Sweden in the 1710s and expanding all the way to Alaska in the east. Finally, after hundreds of years of Tartar control, southern Ukraine and Crimea was annexed in 1783. Russia imposed Orthodoxy by force in this case, kicking out the Muslim Tartars and colonizing the land with Ukrainians and Russians. Therefore, with the exception of the Muslim areas in the Balkans that remain to this day, the European region was fully Christianized sometime in the 18th century.