The usage in early secular documents throws light upon its meaning. In the sentence “whom no one would trust, even if they were willing to work,” we see its meaning of confidence in the person’s character and motives. The sentence “I have trusted no one to take it to her,” speaks of a person’s lack of confidence in the ability of another to perform a certain task. From the standpoint of the one trusted we have “I am no longer trusted, unless I behave fairly.” Paul uses the word in I Thessalonians 2:4 ; Galatians 2:7 ; I Corinthians 9:17 ; and I Timothy 1:11 “I was put in trust with the gospel, the gospel,…was committed unto me, the gospel…which was committed to my trust.” This is the verb usage. When we come to the noun, we have the meaning of “faith and confidence, fidelity and faithfulness.”
The adjective gives us “faithful and trustworthy.” Paul uses the word in his directions to the Philippian jailer, “Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house” (Acts 16:31 ). He exhorts him to consider the Lord Jesus worthy of trust as to His character and motives. He exhorts him to place his confidence in His ability to do just what He says He will do. He exhorts him to entrust the salvation of his soul into the hands of the Lord Jesus. He exhorts him to commit the work of saving his soul to the care of the Lord. That means a definite taking of one’s self out of one’s own keeping and entrusting one’s self into the keeping of the Lord Jesus. That is what is meant by believing in the Lord Jesus Christ.