In many churches, communion is proceeded by a time of reflection to examine oneself for any unrepentant sin. Don’t get me wrong, it is important to repent of sin, but communion isn’t about that. It’s not about us or what we have done. It’s about what Jesus did for us on the cross. The focus should be on Him and his sacrifice.
If you take the entire content of 1 Corinthians 11 in context, there is a problem in the Corinthian church. The prevailing thought in that time was that people ate by age, gender, and wealth. Rich men ate first and poor toddlers last. If there wasn’t enough food, those near the bottom of the pecking order didn’t get any. When the church got together in Corinth, they were following this protocol. The attitude among the wealthier was that they didn’t need to wait for those servants who were likely to come in last because of their work. In doing so they were judging some as better than others. This admonition to judge ourselves has to do with recognizing that we are no better or worse than anyone else.
To drink the cup “unworthily” does not have anything to do with who we are or what we have done. To “not discern the LORD’s body” is to reject others as not worthy. It has nothing to do with a “salvation” prayer or examining ourselves for every little sin. It is recognizing that I am no better than anyone else in the church. To reject a child, or disqualify anyone (even yourself) as “unworthy” of communion because of “sin” is in essence, rejecting the work that Jesus did.