First off, I’d like to thank you for your dedication to presenting the valuable information available on this website. I know that God will continue to bless your efforts.
As for my question, it’s sort of an offshoot of the use of the building and eating in the building. I’ve been studying various topics with my nephew, and recently he asked (without an agenda – he just wants a real answer) why it is wrong to bring in a cup of coffee to the class before the worship service? He was doing just that a few years back when one of the members told him it was a violation of Paul’s command to eat meals in a non-co-located time and place with the gathering of the saints for study and worship (I Corinthians 11:34). I agreed with that, but then my nephew said, “but I don’t see how it’s any different than the bottles of water we have in the foyer.” Uh...well, after sputtering out something about this possibly being a difference between expedient aids (water?) and items more commonly understood as enjoyable “food and drink,” I apologized and admitted that we both needed more study on the topic.
Can you possibly point me toward the guiding principle in this particular issue? Again, thank you for what you’re doing.
The discussion regarding eating as a church activity has become one where people over the years have lost sight of the true issues. Catchphrases have taken the place of reason and people uphold traditions rather than going back to the Scriptures. Therefore, before we get to your specific question, it is best that we first understand why Paul said that meals don't belong in the assembly. See: Kitchens and Fellowship Halls: What Was the Issue?
Typically the reason to discourage bringing drinks, such as coffee and soda, is because accidents happen and cleaning up spilled drinks is difficult. Water is much easier to deal with. That people confuse practicality with the actual issues is understandable.
An issue that arose during the first century was whether meat that might have been from an offering to an idol could be eaten by Christians. While there was nothing wrong with buying and consuming meat found in the marketplace, Paul observed, "Therefore, if food makes my brother stumble, I will never again eat meat, lest I make my brother stumble" (I Corinthians 8:13). Thus, if a brother thinks drinking coffee at a Bible study is wrong, then the best choice is to not bring coffee and bother the brother.