157 Q. Now that we have discussed the various articles and parts of articles of the confession of our Christian faith, I would like to hear from you whether we shall be fully saved through such true faith in Christ?
A. There is only one way to eternal life (as I also said at the beginning of these articles), namely, the crucified Christ accepted through a true faith (1 Cor. 2:2). Since, then, faith (which is a gift of the Holy Spirit) possesses Christ and all His benefits as its own, and Christ is the one freely given us by God to be ours through faith, one of two things must follow: either Christ does not have all that is necessary for our salvation, or, if He does, one who possesses the crucified Christ through a true faith also has everything in Christ that is necessary for salvation.
Through all the Articles of Faith it has been demonstrated that everything necessary for our eternal salvation is in Jesus Christ and that He was not a partial but a complete Jesus, or Savior, who fully accomplished everything necessary for our salvation. Therefore, whoever is grafted into Christ through a true faith has and possesses everything within that is necessary for salvation.
Caspar Olevianus, Firm Foundation (Grand Rapids: Baker, 1995), 108.