The article repeats what I have been taught all my life.
Christmas - Saturnalia
Christmas Tree - Druids would decorate trees (they did not cut them down)
Easter(Eoster goddess) - Spring Fertility Celebration (rabbits/eggs)
Sacrement - Jewish Kiddush (performed every Friday night with wine and bread)
Baptism - Jewish Mikvah (immersion in water is done frequently throughout the year)
When Christianity was new and sought to expand, they simply incorporated whatever the local customs were and 'Christianized' them. You can keep doing whatever it is you do, just say you are doing it for Jesus and it's all good. Thus, Christianity is kind of a mishmash religion composed of elements of several different traditions and cultures. However, from a Christian point of view, this does not necessarily detract from the divinity of Jesus or the central core of the religion. My understanding of Christianity is that it is primarily a 'faith'. The Holidays are just for fun. It doesn't really matter if Jesus was actually born on Christmas. To reserve a day for the celebration of his birth, whenever it was, is enough.
That's my two cents anyway. For what it is worth.