how do you tell you family that you ain't that religious

they want to go to a place of worship and want to go as a family for Christmas as everyone is free but I have a hard time communicating so if you can help me with a way to say it ps I'm Christian all

my family and friends are Christian it very peer pressure (I have a huge community with everyone being majority Christianim talking about 200 people)as they want me to do this thing called a confirmation and I've been avoiding it

help me with things I can say to my family about my beliefs (agnostic)