There is a lot of controversy behind the allowing of tattoos and piercings in the modern church today. Is it really sinful for a Christian to get a piercing or tattoo? The conversation starts with a command given in Leviticus 19:28 saying,"You shall not make any cuts on your body for the dead or tattoo yourselves: I am the Lord."
The book of Leviticus is essentially a database of over 600 commandments that God gave to the people of Israel as they prepared to enter the promised land. Many of these laws are universal in principle staying timeless and true until today.
But there were also many laws in the Bible that were more civil and cultural than they were principle-based. Some of those laws included laws on slaves, dietary restrictions and so on. The prohibitions of tattoos and piercings fell under this category meaning there is a chance that it no longer applies to today's modern context.
To know whether a law applies or not, we must come to understand why such a law was given in the first place. God prohibited tattoos and piercings as a means to set people apart from pagan tribes that used these practices as worship to their gods and deities.
God prohibited tattoos and piercings not because of the act itself but because of the spiritual association it had. Today, tattoos and piercing are no longer exclusively used for paeanistic practices.
The New Testament never mentions the topic of tattoos and piercings and people have taken this as a signal that it's no longer prohibited. But what matters more than anything is the heart of why we do what we do.
Jesus summed up all commandments into one- "You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and first commandment. And a second is like it: You shall love your neighbor as yourself." (Matthew 22:37-39)
What matters to God is not what you do, but why you do what you do. You can abstain from tattoos yet do them for the wrong reasons such as to hold hateful judgment upon those who do. On the other hand a Christian might get a tattoo of a verse or statement to serve as a constant reminder of God's Word and promises.
In addition, what matters to God is not the external appearance, but the internal character. In 1 Peter 3:3–4, it says, "Your beauty should not come from outward adornment, such as elaborate hairstyles and the wearing of gold jewelry or fine clothes. Rather, it should be that of your inner self, the unfading beauty of a gentle and quiet spirit, which is of great worth in God's sight."