Catholicism.
The three major religions in Europe include Christianity, Judaism, and Islam. Of the three, Judaism is the oldest.
Christiaity
Hinduism is the oldest surviving religon. It's in the top 3 so i guess it is "major"
Christianity I believe
catholism
Greek Orthodox
irreligion
Catholics
Muslim and Catholic.
The major religion of Finland is Evangelical Lutheran Christianity.
Muslim and Jewish and Christian.