A Question About The Saints

[Indeependent]

I was just thinking about this since today is my birthday. Why do we celebrate Valentine's Day and Saint Patrick's Day on the days they died rather than the days that they were born?

St. Valentine's Day
Look up the origin and you will be shocked.

 

[Road Runner]

St. Valentine's Day
Look up the origin and you will be shocked.

I already know the origin and I was shocked.