We might know that the Vikings had festivals resembling Halloween. It is the Alfablot and the Disablot. The Vikings also celebrated a festival known as Yule. The Viking Yule celebration was similar to the modern Christmas. In fact, customs and traditions from modern Christmas stem from the Yule celebration of the Vikings.
Regarding the custom of burning the dead, not only the Vikings did so, but also many other people from other regions. But one cool thing in the Viking community was that they burnt their longhouse when a person was dead. Nothing about the Viking culture was unreasonable. It was just because we don't understand it. This blog post is to help make sense the custom of burning the longhouse in the Viking days.