The words, “the faith” is not a reference to personal faith or trust in or on something or someone. It is a body of truth revealed by the Spirit. To demonstrate this, consider the following biblical passages. First, Acts 6:7 reads, “And the word of God continued to increase, and the number of the disciples multiplied greatly in Jerusalem, and a great many of the priests became obedient to the faith.” This text explains that many people obeyed the faith or became obedient to the faith. The number of disciples being multiplied is commensurate with a great many priests being included in that number. Yet, both correspond to the word of God continuing to increase. The word of God that increased was responsible for the increase of the number of disciples. In addition, the last statement is comparable to the first as is refers to a great number of priests who obeyed the faith. To obey the faith is to obey the word of God. Similarly, the increase of the word of God is the same as the faith continuing to increase. Paul is said to “preach the faith he once tried to destroy” (Gal. 1:23). Likewise, Timothy was “trained in the words of the faith and of the good doctrine that he followed (1 Tim. 4:6).
Second, Acts 13:8 records Elymas, the magician, opposed Paul and Barnabas, seeking to turn the proconsul away from the faith. The same faith that one can obey can also be turned away from or rejected. Paul’s teaching of the word caused the proconsul to accept the faith, but Elymas opposed him, seeking to undo his teaching by persuading him to turn away from “the faith” or the word (cf. 1 Tim. 4:1, “depart from the faith”; 1 Tim. 6:10, “wander from the faith, 6:21).
Third, one can be encouraged to continue in the faith, despite the tribulations that are faced. Acts 14:22 tells us that Paul “strengthened the souls of the disciples, encouraging them to continue in the faith, and saying that through many tribulations we must enter the kingdom of God.” Similarly, he writes, “if indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that you heard, which has been proclaimed in all creation under heaven, and of which I, Paul, became a minister” (Col. 1:23). The saints (the called-out) were ”strengthened in the faith and increased in numbers” (Acts 16:5). He describes the saints in Colosse of being “rooted and built up in him and established in the faith, just as you were taught, abounding in thanksgiving” (Col. 2:2). Being established and strengthened in the faith can only be accomplished by being “taught.” Paul wrote to the Corinthians to “stand firm in the faith” and to be strong (1 Cor. 16:13). Paul writes of the “progress and joy in the faith” in Philippians 1:25.
Fouth, Paul writes, “Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you?—unless indeed you fail to meet the test! (2 Cor 13:5). He encourages saints to stand firm in one spirit, striving for the faith of the gospel (Phil. 1:27). The same verse speaks of one’s manner of life is worthy of the gospel of Christ.
Fifth, Paul refers to Timothy as his “true child in the faith” (1 Tim. 1:2). Paul had taught him sound doctrine and Timothy was to preach the word (2 Tim. 4:2) and hold fast to that which he had been taught.
The unity of the faith in Ephesians 4 is the unity of the faith of the gospel. It not only produces unity by bringing together of two one new man, but it is by nature one (Eph. 4:4). There is one faith for which the saints must contend and for which we must fight and strive.
The body of Christ, not churches, has attained that unity of the faith to a complete, mature man. This is not a reference to the flawless perfection of individual saints. It is referring to the uniting of Jew and Gentile into one body by accepting the one faith of the gospel that makes no distinction between male or female, bond or free, Jew or Gentile. Each member of the body supplies a need to each other member so that there is consistency and harmony in building up itself in love. (Eph. 4:14-16).