What does 1 Thessalonians 2:1 mean?

Paul reflects on his missionary venture in Thessalonica. It was not unproductive. As 1 Thessalonians 1:9 reports, Paul's readers had become his brothers. They had turned away from idolatry and had become servants of God, and they were anticipating Jesus' return from heaven. When God's Word is sent out, it always accomplishes the purpose God had in sending it. That message may fall on some hearts that are like rocky ground and become scorched by the sun; or it may fall on some hearts that are like a path on which birds devour the seed; or it may fall on some hearts that are like thorny ground that chokes the seed (Mark 4:1–9).

However, God's Word will surely fall—eventually—on good soil and produce an abundant harvest. Isaiah 55:10–11 relates a similar message about God's Word. He promises, "For as the rain and the snow come down from heaven and do not return there but water the earth,making it bring forth and sprout, giving seed to the sower and bread to the eater, so shall my word be that goes out from my mouth; it shall not return to me empty, but it shall accomplish that which I purpose, and shall succeed in the thing for which I sent it."