Ever wonder who is in the "salvation generations" since the shepherds began spreading the word that they heard about Jesus? In other words, the shepherds began sowing the seed of the Good News about Jesus. Where has that seed spread down through the years? We can trace some efforts of the various apostles as to where they went and the nations who heard about Christ through them. But the apostles weren't the only ones spreading the Word. The shepherds did, the various recipients of Jesus' miracles did, even the Roman soldier at the foot of the cross did when he said, "Truly this was the Son of God" Matthew 27:54.
Who has already heard about Jesus and who will hear about Him because YOU have shared the gospel with others? The Lord has a wonderful way of spreading the seed even though the first "kernel" fell 2,000 years ago! Who will hear the good news about salvation because you handed out a tract or gave a Gospel of John to someone? God keeps records. One of the joys of heaven will be finding out the chain of witnesses God used to bring salvation to us! Keep on spreading the Word!