A reading of Paul's letter to the Galatian Christians reveals that the Apostle put all people into two categories. It had nothing to do with being Jew or Greek, male or female, slave or free. There were those who chose to "live by the Spirit" (Galatians 5:25) and there were those who live to "gratify the desires of the flesh." (Galatians 5:16). It is clear that it is an "either-or" choice. The two life choices are not compatible. Anything less than an absolute surrender to the life in the Spirit means that the choice is to gratify the desires of the flesh. There is no room for any kind of compromise in the heart.
While it is true that Jesus was talking about wealth when He said, "No one can serve two masters..." (Matthew 6:24) it is equally as true that we cannot live according to the Holy Spirit and the life of the flesh which the evil one entices us to embrace. The Scripture characterizes those who live according to the flesh by saying, ""Now the works of the flesh are obvious: fortification, impurity, licentiousness, idolatry, sorcery, enmities, strife, jealousy, anger, quarrels, dissensions, factions, envy, drunkenness, carousing, and things like these." ((Galatians 5:19-21) What is described here is the undisciplined, out of control life of a self seeking ego.
On the other hand those who live by the Spirit are bearers of "love, joy, peace, patience, kindness, generosity, faithfulness, gentleness, and self control." (Galatians 5:22-23) These characteristics are called "the fruit of the Spirit" meaning that they are produced from within the heart by the Holy Spirit. Those who choose life in the Spirit submit themselves to the controlling influence of the Holy Spirit so that their hearts begin to resemble the heart of Jesus. Those who live according to the Spirit live not to satisfy the undisciplined ego, but to live according to the will of God. Such is our choice.