Summary: The first two works/deeds of the flesh here in Galatians 5, fall generally into the two pitfalls of: 1) Sexuality (Galatians 5:19), and 2) Religion, (Galatians 20a)
People mark off times and celebrations in different ways. In Belgium (since 1394, in Binche), Brazil (a four-day celebration in Rio de Janeiro), Italy (in Venice, six months of celebrating in the 18th cent., now 12 days), Trinidad and Tobago (featuring a daylong competition among calypso bands), and the United States (most notably, the New Orleans), as well as other regions, people have just finished an elaborate festival (Fahlbusch, Erwin ; Bromiley, Geoffrey William: The Encyclopedia of Christianity. Grand Rapids, Mich.; Leiden, Netherlands : Wm. B. Eerdmans; Brill, 1999-<2003.).
Universally, this celebration is known as “Carnival” or Mardi Gras specifically in New Orleans. Carnival comes from a combination of Latin words meaning "farewell to the flesh." There is a great deal of irony in that name because there is by no means a time when the desires of the flesh are denied or bid farewell. Instead they are lavishly indulged. Anything goes—gluttonous eating, massive consumption of alcohol, even public displays of sexual immorality (to say nothing of what goes on behind closed doors). The streets, sidewalks, shops, and hotels on Bourbon Street in New Orleans are indeed X-rated during this festival of debauchery.
So why the name "farewell to the flesh"? Carnival or Mardi Gras coincides with the traditional last day before the fasting season that some practice as Lent, a 40-day period of self-denial and repentance, instituted by some in the early church as a way of preparing Christians for Easter. The beginning of this period is known as Ash Wednesday, so the final day of Carnival is known as Shrove Tuesday. The word "shrove" is derived from the Latin scribere, meaning, "to prescribe penance." During the middle ages, religious leaders would ensure that "shriveners" (priests) were available to hear the confessions of the multitudes of presumptuous sinners who had committed all types of iniquity during Carnival.
The job of the priest was not to call these people to a deep and true repentance, but rather to prepare them ceremonially for Lent. In other words: Have your fun! Drink as deeply as you need of the lusts of the flesh! Just be sure to confess your sins to the priest before Lent. The priest who hears your confession will prescribe fasting and the right sort of penance (self-inflicted penalty) for you to make amends with God. (Daryl Wingerd @ http://www.ccwblog.org/2009/02/heres-skinny-on-fat-tuesday.html)
Paul has shown that no human work, penance or otherwise, can atone or repair a broken relationship with God, which sin achieves. The Judaizers claimed that Paul’s teaching would encourage people to forsake all restraint, and indulge in all types of sins. Paul however showed that no external system, law or otherwise, could restrain sin. It could only be achieved though the supernatural work of Holy Spirit. The Holy Spirit enables godly obedience called walking in the Spirit. The fruit of the Spirit is the natural result of walking in the Spirit.
But what about those who do not walk in the Spirit? God says they walk in the flesh, with the objective and pattern of life which can be externally seen as the deeds of the flesh.
Paul specifies in:
Galatians 5:19a Now the works of the flesh are evident: (sexual immorality, impurity, sensuality), (ESV)
“Works” (in the plural) are attributed to the “flesh,” because they are divided, and often in conflict with one another, and even when taken each one by itself, betray their fleshly origin. But the “fruit of the Spirit” (Ga 5:23) is singular, because, however manifold the results, they form one harmonious whole (Jamieson, Robert ; Fausset, A. R. ; Fausset, A. R. ; Brown, David ; Brown, David: A Commentary, Critical and Explanatory, on the Old and New Testaments. Oak Harbor, WA : Logos Research Systems, Inc., 1997, S. Ga 5:19
cf. confer (Lat.), compare)
The works/deeds of the flesh reflect the sinful desires of unredeemed humanness, which are in spiritual warfare against the desires of the Spirit (vv. 16–17; cf. 24).
• As we have seen, “Flesh” the N.T. often employs the term to designate the sinful tendencies that exist in people, most of which are related to bodily appetites and ambitions (Believer’s Study Bible. electronic ed. Nashville : Thomas Nelson, 1997, c1995, S. Ga 5:13)
o The works of the flesh are hereby spelled out. These works/deeds are so evident that Paul mentions them primarily by way of a reminder.
o Evident/which are these—Greek, “such as,” for instance.
Matthew 7:16 You will recognize them by their fruits. (Are grapes gathered from thornbushes, or figs from thistles?) (ESV)
Though the sins that Paul lists here in Galatians 5 (cf. Rom. 1:29–31; 2 Cor. 12:20–21) are natural characteristics of unredeemed humanity, not every person manifests all of the sins or manifests them to the same degree. However, every person possesses the flesh, which is sinful and will therefore be manifested in sinful behavior, whatever the particular forms of it may be. These are normal and continual behaviors for unbelievers in their course of life in the flesh, but are abnormal and interruptive behavior in the lives of Christians, who live in the Spirit. A Christian can walk in the Spirit and avoid them all, or they can give in to the flesh and fall victim to any of them.