G'day Guys,
Interesting thread, thought I might put my thoughts on the matter forward...
....I think a hobby (or anything) for that matter becomes sinful when it becomes an "idol".
If you put a hobby or activity ahead of where you place God in your life it is not a good thing.
As Christians God should take number one posi in our life, with the other things coming in after.
Having said that though, I think God wants us to have a full and complete life, which includes other interests outside the spiritual.
Everything in its correct order: God, family, work and HOBBIES
Best Wishes,
Rob.