What does 2 Peter 2:13 mean?
Peter continues describing the sins and impending judgment of false teachers. These men have been attempting to lead the original readers of this letter away from the truth of the gospel of Jesus. In this verse, Peter writes to assure his readers that the false teachers will not get away with what they're doing. As much as they seem to be succeeding in the present moment, they will suffer wrong as the payment for the wrong they are doing. God is paying attention; judgment and destruction will follow.One of the characteristics of these false teachers was an indulgence in sexual immorality. Peter now writes that they are so bold about their sin that they carouse or revel in their immorality in broad daylight. They lack even the shame to hide their sinful choices under the dark of night. In a more modern sense, this is the "loud and proud" attitude. Those who take this approach do not hide their sin, and are not subtle about it. Instead, they parade it for others to see.
Peter reveals that these false teachers are disfiguring the church. This is in the same way a stain or blemish might mar a shirt, for instance. They feast with the true believers while continuing to tell their lies about who Jesus is. This feasting Peter mentions may refer to immoral partying that people in the church were being lured into by these false teachers. Or it may be that the false teachers were attending the official gatherings of the early church, which included taking part in the Lord's Supper, creating a serious "stain" on that meaningful time before God.
This relates to an important point about church purity. Paul makes the point in Ephesians 5:3 that certain kinds of immorality should not be tolerated within the community of the church. It can be difficult to strike a balance between loving sinners, and not accepting sin. However, it is important for the church to stand for moral conduct. At some point, associating with an unrepentant sinner damages the reputation of the church, interfering with the spread of the gospel.