Question: Do we then participate in Christ and all His benefits only by a true faith and trust in the promise of God in the gospel?
Answer: By faith or trust alone. John 1:12 “As many as received Him, to them He gave power to become the sons of God.” And it is certain that these two statements mean the same thing: “By faith alone we become righteous” and “By faith or trust alone we accept Christ, who is our righteousness.” For in both statements faith grasps the promise of pardon for sin for Christ’s sake; by this alone we become righteous before God. In sum, Christ is offered to us by the Father in no other way than through the foolishness of preaching, or the promise of the gospel (1 Corinthians 2). Hence he cannot be accepted in any other way than by believing the promise of the gospel in one’s heart.
Caspar Olevianus, A Firm Foundation, p. 11