Answer: God's Word--the Word that is planted in and humbly accepted by His children--can save them, (verse 21).
MORE INFORMATION AND/OR OTHER SCRIPTURE REFERENCES:
Matthew 13:1-9: "That same day Jesus went out of the house and sat by the lake. Such large crowds gathered around Him that He got into a boat and sat in it, while all the people stood on the shore. Then He told them many things in parables, saying: ‘A farmer went out to sow his seed. As he was scattering the seed, some fell along the path, and the birds came and ate it up. Some fell on rocky places, where it did not have much soil. It sprang up quickly, because the soil was shallow. But when the sun came up, the plants were scorched, and they withered because they had no root. Other seed fell among thorns, which grew up and choked the plants. Still other seed fell on good soil, where it produced a crop--a hundred, sixty or thirty times what was sown. He who has ears, let him hear.'"
Matthew 13:18-23: [Jesus said,] "Listen then to what the parable of the sower means: When anyone hears the message about the kingdom and does not understand it, the evil one comes and snatches away what was sown in his heart. This is the seed sown along the path. The one who received the seed that fell on rocky places is the man who hears the Word and at once receives it with joy. But since he has no root, he lasts only a short time. When trouble or persecution comes because of the Word, he quickly falls away. The one who received the seed that fell among the thorns is the man who hears the Word, but the worries of this life and the deceitfulness of wealth choke it, making it unfruitful. But the one who received the seed that fell on good soil is the man who hears the Word and understands it. He produces a crop, yielding a hundred, sixty or thirty times what was sown."
Ephesians 1:13-14: "And you also were included in Christ when you heard the Word of Truth, the Gospel of your salvation. Having believed, you were marked in Him with a seal, the promised Holy Spirit, Who is a deposit guaranteeing our inheritance until the redemption of those who are God's possession--to the praise of His glory."
Romans 1:16-17: "I am not ashamed of the Gospel, because it is the power of God for the salvation of everyone who believes: first for the Jew, then for the Gentile. For in the Gospel a righteousness from God is revealed, a righteousness that is by faith from first to last, just as it is written: ‘The righteous will live by faith.'"
Romans 16:25-27: "Now to Him Who is able to establish you by my Gospel and the proclamation of Jesus Christ, according to the revelation of the mystery hidden for long ages past, but now revealed and made known through the prophetic writings by the command of the eternal God, so that all nations might believe and obey Him--to the only wise God be glory forever through Jesus Christ! Amen."
1 Corinthians 15:1-2: "Now, brothers, I want to remind you of the Gospel I preached to you, which you received and on which you have taken your stand. By this Gospel you are saved, if you hold firmly to the Word I preached to you. Otherwise, you have believed in vain."
