How does God normally bring people to a knowledge of salvation?
God normally brings people to salvation through human instruments, not angels. He has committed His Word to people, and He almost always uses one person to share Scripture with another, so that a heart is opened and that person attends to the message and becomes a believer.
Les teaches that God did not leave the Word in the hands of angels but in the hands of people. He has almost always used one human instrument to lead another human to a knowledge of salvation. That is why Les urges believers to learn and get skilled in Scripture, so that when an opportunity comes they can simply show someone what the Word says. The example is Lydia: her heart was opened, she attended to Paul's words, and she became a believer when she was baptized. Les notes this was during the transition period, when baptism was still part and parcel every time Paul had a convert, though he maintains the importance of baptism later drops away as fuller revelations come.