There were many different "pagan" religious traditions in Europe at this time. Of course, the most famous pagans of the Viking age were the vikings themselves, but at the time most of Eastern Europe was still pagan.

Vladimir of Kiev adopted Christianity in 988 well into the Viking age, roughly defined from 793 to 1066 (the raid on Lindisfarne and the defeat of the Norwegians under Harald Hardraade).

Lithuania and the Baltics remained pagan until well into the middle ages. Lithuania itself did not convert to Christianity until 1251 when, the poorly attested admittedly, King Mindaugas accepted Baptism for himself and his family.

Now as for Ireland/Celtic regions specifically, it is unlikely that there were still pagan hold outs at this stage. Ireland and Wales had been Christianized long before the vikings started raids in Western Europe. I cannot really speak to Brittany or Scotland at this time, but I would be surprised if they had any pagan settlements at this stage.

Now of course it is impossible to definitely say that there were no pagan settlements in Celtic areas at this point, but it is exceedingly unlikely.