That measure of faith is inherently pointing at the object which the believers have put their faith and thus performs a complete leveling influence to Christian living. Note how aptly Paul draws the Measure of Faith in the area of the Church Body.
In Corinthians Paul speaks about the uniqueness of each individual member of the body and those unique members working with a specific function in the whole but here Paul uses the illustration to highlight the cohesiveness of the body.
Many members: one body. Different functions: Christ’s body. Individual members: members of one another. Each of us given gifts according to God’s grace: Each of us using them for the purpose of the body.
The Gospel allows an individual to drop his individualistic focus for the greater extent of the body for it was God’s grace that allowed a believer to be saved and be gifted therefore he is no longer his own: let him serve.
Service then is not done to the extent of “I’m doing my service more than X individual but less than Y person” but rather “Since I live by God’s Gospel then I will serve as God has gifted Me.” Therefore teaching is not “I am a better teacher than X but not as good as Piper” but “Since I live by God’s Gospel and He’s gifted me to teach, therefore I will teach.” Not looking left or right, but looking on the place which we stand and for the purpose of which we’re gifted: for other believers.
Service, teaching, exhortation, giving, leading, mercy: all of them to the fullest extent of the gift itself for the body of Christ. So that means that being merciful to a person isn’t just contributing to people’s needs but actually doing it with cheer so that the person is supported to the fullest extent of God’s gift. This full execution of the gift is the practical giving preference to one another in brotherly love without two-facedness.
It is honest to goodness, all out, full-on contributing to the needs (physical and spiritual) of the saints which are Christ’s body.