Question: where in the bible does it say not going to church is a sin?
Answer: 2 Corinthians 13:1 This is the third time I am coming to you. In the mouth of two or three witnesses shall every word be established. To answer your question directly, it's not a sin to miss church, but we are admonished to gather with believers so we can “exhort and provoke each other unto love and good works”.