The NT is clear that, since Pentecost, God uses people as his exclusive means to teach others the gospel. He goes to a lot of trouble to get his people to evangelize. Even when talking directly to the unsaved in the NT, the Lord never tells them directly what to do in order to be saved. He leaves this to the church, since he has given them the task of telling. Chapters 8, 9, and 10 of the book of Acts show this clearly.
- Philip to the eunuch, Acts 8.26-29:
Then an angel of the Lord said to Philip, “Get up and go south on the road that goes down from Jerusalem to Gaza.” (This is a desert road.) So he got up and went. There he met an Ethiopian eunuch, a court official of Candace, queen of the Ethiopians, who was in charge of all her treasury. He had come to Jerusalem to worship, and was returning home, sitting in his chariot, reading the prophet Isaiah. Then the Spirit said to Philip, “Go over and join this chariot.”
- Ananias to Saul. In Acts 9.6 Jesus said to Saul:
But stand up and enter the city and you will be told what you must do.
- Peter to Cornelius, Acts 10.21-22:
So Peter went down to the men and said, “Here I am, the person you’re looking for. Why have you come?” They said, “Cornelius the centurion, a righteous and God-fearing man, well spoken of by the whole Jewish nation, was directed by a holy angel to summon you to his house and to hear a message from you.
In every case in the NT, a Christian told another what to do to be saved. Even when God intervened miraculously to bring saint and sinner together, as he did in Acts 8, 9, and 10, he stopped short of teaching the gospel directly.
So it is today. If you don’t, God won’t.
But you are a chosen race, a royal priesthood, a holy nation, God’s own people, in order that you may proclaim the mighty acts of him who called you out of darkness into his marvelous light. 1 Peter 2.9 NRSV.