A hot-air balloon goes up as you give up the weight that holds you down.  That's how it is when for a Christian. Christianity is more about giving up and less about going up. Going up is the result of giving up. When we give up, we go up.  When we go up, we look back and realize that it took giving up to go up. 

Paul was willing to give up what he had in order to help Onesimus.  As he gave up, he found himself going up.  Here we are, almost 2,000 years later, reading a letter about what Paul was willing to give up. 

This one statement captures Paul's heart: 

"If he has wronged you at all, charge it to my account." Philemon 18 

In this letter, Paul makes an appeal, set's an appointment and shares his appreciation.  It was all about helping someone who could do very little for him in return.

It was written so that they would know the grace their creator placed upon their lives and what they should do with that grace. This letter helps them to grow in understanding of God, receive knowledge of their identity in Christ, advance in wisdom, cooperate in order, and endure the battles.

Ethnicity

Paul is a Jew speaking to Gentiles (a region of mostly Celtic Gauls) about how salvation, through Jesus Christ, works for all people. The emphasis of this letter comes because a group of Jews (historically known as the Judaizers) were teaching these Gentile Christians to live according to the Jewish Law and follow Jewish customs. Paul is calling them back to embrace the new ethnicity they embraced called "the way." Paul does not have to stop being a Jew to be a Christian and the Galatians do not have to stop being Celtic Gauls to be Christians.