Celebration can be good
The Bible does not treat celebration as unspiritual. Jesus attended a wedding in Cana (John 2:1-2), and his first sign there provided wine when the wedding feast had run short (John 2:7-10). Marriage is a good gift from God, so friends rejoicing with a bride or groom can be fitting.
A bachelor or bachelorette party itself is not a biblical requirement. Some couples will love a restaurant meal, hiking day, craft night, sports activity, or quiet gathering with close friends. Others may skip it completely. Neither choice makes someone more spiritual.
Whether therefore ye eat, or drink, or whatsoever ye do, do all to the glory of God.
Let the purpose set the tone
Paul's guidance for everyday choices gives a helpful test: can this be done for God's glory (1 Corinthians 10:31)? That question reaches beyond the invitation. It includes the venue, spending, jokes, entertainment, alcohol, photos, and what people expect will happen after dark.
A good party does not need to be dull. Laughter, affection, good food, and stories of friendship can honour the person about to marry. But if the point is to mock commitment, act single one last time, or push people into things they would rather keep hidden, the celebration has lost its way.
Protect purity and clear thinking
The days before a wedding are not an exception to Christian faithfulness. Paul calls believers to turn from sexual immorality and to practise self-control with their bodies (1 Thessalonians 4:3-4). Planning boundaries beforehand is wiser than hoping everyone will make good choices in a pressured moment.
Christians differ in how they approach alcohol, but Scripture is clear that drunkenness is not the goal of a celebration (Ephesians 5:18). If drinking is likely to lower inhibitions, stir old temptations, or leave someone unsafe, choose another plan. That is not being joyless. It is taking care of people.
And be not drunk with wine, wherein is excess; but be filled with the Spirit;
Make room for your friends
Love does not build a party around pressure. Paul tells Christians not to place a stumbling block in another believer's path (Romans 14:13). Someone invited may be avoiding alcohol, recovering from addiction, uncomfortable with sexualised humour, short of money, or simply carrying a sensitive conscience.
So plan in a way that lets people join freely and leave with peace. Ask yourself: would this help my friends honour Christ and encourage the coming marriage? If so, gather gratefully. A thoughtful celebration can become more than a party. It can be a group of friends blessing a new home before it begins.