"All things are lawful for me," but not all things are helpful. "All things are lawful for me," but I will not be dominated by anything. 1 Corinthians 6:12
The conversation about dress code in the church is neither as new nor as old as we probably think it is. Even in Paul's day, he instructed the church in what was appropriate attire for both men and women. What he has to say about this topic is, not surprisingly, unpopular today. However, he doesn't address the topic as "what should you wear when you're gathered together as Christians", no, he addresses the topic as "what is appropriate for Christians to wear in their everyday life. He also directly addresses the struggles the Church was having in the culture of his day, so some of the specific references to styles like plaiting may not be applicable today depending on how far into legalism you want to go. With that in mind, let's walk through this topic to get at the heart of how the Church was instructed to dress.
It's Not About Your Clothes, It's About Your Heart
Do not let your adorning be external -- the braiding of hair and the putting on of gold jewelry, or the clothing you wear -- but let your adorning be the hidden person of the heart with the imperishable beauty of a gentle and quiet spirit, which in God's sight is very precious. 1 Peter 3:3-4
This particular passage has been taken out of context so many times to mean that a woman shouldn't braid her hair, wear jewelry, or wear fancy clothes if she is a Christian. Really this is saying almost the exact opposite of that. It's saying that anyone can make themselves externally beautiful, but that does not change the condition of their heart, soul, or character. Just as someone could be wearing rags, but be redeemed in Christ and their life through suffering a true testament to the goodness of God.
In older churches, the respectful thing maybe as a man to remove your hat when you enter the building. In previous generations, it was common practice to do so whenever you entered any building be it your home, a restaurant, or other public gathering places. As we moved away from that sign of respect the practice carried on for government buildings and churches. Similarly, women used to dress up in their "Sunday best" usually a pretty dress to go to Church, not because it was Biblically required of her but because in our culture that was a sign of honor to the place of gathering. Today, many churches don't require either formality and urge people to come as they are. Every once in a while the two groups clash, what I would argue both should remember is that God isn't necessarily looking at the fancy outfit someone did or did not put on to attend, He is looking at the state of their heart.
Be careful! That while you are putting on your finest for the Sunday service that you're also taking stock of whether you are right with God. Don't be like the religious people of Jesus' day whom He called out for looking so outwardly righteous to everyone else while inside they were as dead as the bones in whitewashed tombs.
"Woe to you, scribes and Pharisees, hypocrites! For you are like whitewashed tombs, which outwardly appear beautiful, but within are full of dead people's bones and all uncleanness. So you also outwardly appear righteous to others, but within you are full of hypocrisy and lawlessness. Matthew 23:27-28
It's Not About Your Clothes, It's About Honoring God
I desire then that in every place the men should pray, lifting holy hands without anger or quareling; likewise also that women should adorn themselves in respectable apparel, with modesty and self-control, not with braided hair and gold or pearls and costly attire, but with what is proper for women who profess godliness -- with good works. 1 Timothy 2:8-10
Again this has been taken out of context to mean that women shouldn't dress to look their best or that if a woman owns expensive clothing then clearly she is not godly. In the day this was written there were women in the church who were wearing fancy clothes and jewelry to lord it over women who could not afford those things. They had taken their eyes off of the purpose of the body of Christ which is to honor God and love one another. Likewise, the men were struggling with all sorts of anger and quarrels. Those things didn't really have anything to do with the clothes the men and women were wearing, they had to do with the condition of their hearts.
In American culture today and I could safely include Europeans in this, there is a real struggle with the topic of modesty. It is difficult to find clothing in stores that could really be defined as modest and the modest clothing we do find seems to be made ugly on purpose. The art of making your own clothes is quickly being lost, if it's not already to the distant past. Americans especially struggle to address this topic because it seems to take on the guise of victim-blaming when we tell women they should dress modestly so as not to tempt their male peers into sin. Men absolutely need to take responsibility for their sexual immorality I will not argue that point! Women, however, also need to take responsibility for their sexual immorality. Using their sexuality as a weapon against men is definitely an example of this.
Here is what it comes down to whether you are male or female...
Is what you're wearing honoring to God?
Could what you're wearing reasonably be accused of being sexually tempting?
Why are you wearing that outfit? Is it to look nice for church or is it to look better than Karen whose outfits on Instagram always seem more expensive and prettier than yours?
You aren't required to be ugly or unfashionable just because you're a Christian. You are required to honor God and love one another even in your appearance.
If you have any other questions about how you should dress as a Christian, please feel free to leave them in the comments below. I've also been thinking about putting difficult topics like these in the Forum so that we can continue this discussion together there. I highly encourage you to find a mentor in the faith who can help personally walk you through many of these issues as you grow into a mature believer. This is one journey you were never meant to take alone!