If this below scripture doesn't correct any person who claims to be a christian and believes that celebrating 25 december as a holyday( christmas day) is evil or that those who worship on saturday or any other day have done no wrong then leave that person till they find out themselves.

The below verse also says that it is not wrong to celebrate the new moon .Even if christians decide to celebrate christmas on the day romans celebrate the new moon it is not wrong,It is just a coincidence.

Colossians 2:16

16.Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath days:

Note:I am not an adventist