Loneliness is not a sin per se. It is often a tormenting temptation to sin. Sinning and then having a guilty conscience while being lonely is a punishing emotional cocktail.
Not everyone who is alone feels lonely. Not everyone who is in a group doesn’t feel lonely. Talking to others might actually confirm your suspicion that you’re not that close and/or that you are not understood. Sometimes loneliness results from others trying to keep you on the outs, other times it comes from your fears about being in.
Lonely doesn’t feel good, and you can make it less good. In a fallen world it doesn’t take two to make a thing go wrong.
Loneliness exists, it can be heavy and acute, more like having the pointy side of the anvil pushing into your chest. Maybe you lost a longtime spouse, maybe you are looking for one for a long time. Maybe your dad never paid attention to you. Maybe you had friends but they started doing other things. Maybe you had friends you expected would keep doing all the work you weren’t. Maybe you are awkward. Maybe God has put you among a group of people you can’t leave but with whom you also can’t fully participate.
I bring up loneliness because the sermon is about gender confusions and sexual corruptions. God made us male or female (Genesis 1:27), and He made us for relationship, which typically manifests in marriage responsibilities between one man and one women. He also unites us in one body of many members (1 Corinthians 12:12). Our Creator formed every human heart for connection, but fallen humans are too easily satisfied.
It is not godly to grumble, and it’s not attractive either. Don’t nurse your loneliness with lust, or lies, whether to those around you or to yourself. Don’t isolate yourself (Proverbs 18:1). Cry out to the Lord; Jesus is a friend for sinners.