Religion and Gods
The Vikings had a Pagan religion in which they worshipped many gods. The most important god was Odin. Odin was the god of poetry and love, and the father of Thor. The Vikings slowly converted to Christian religion as they found it was easier to trade with people if they shared the same religion.
Beliefs
They Vikings thought that it was cowardly to die in bed as opposed to being killed in battle. Dying anyway other then war meant that there body would be sent away to the equivalent of hell. If you died in war your sole travelled to Valhalla, where you could battle and feast with Odin for the rest of eternity.
Stories and Writing/Written Communication
At the start, Vikings had two alphabets which consisted of runes. Later in the 12th century, they converted to the Latin alphabet. They used letters and runes to engrave gravestones and write stories. They wrote Norse Myths, which were myths about gods, giants and monsters. The fact that Vikings could write is virtually the sole purpose we know about them today.
Festivals/Celebrations and Culture/Traditions
The Vikings had a sort of Yuletide tradition which pre-dates all Christian ideas of the holiday. It was definitely a different event from the one we know today. One of the traditions the Vikings had was a festive tradition called Yulellog. They used to get thick oak logs and carve faces and runes into them, kind of like a totem pole. They burned part of the log and kept the other part to light the following years fire.