What does Mark 4:29 mean?The application of the parable of the growing seed is the work of the Holy Spirit in evangelism and spiritual growth. The teacher spreads the gospel, the students hear it, but it is the Holy Spirit who causes the message to make a difference in the lives of the hearers.
That difference includes a better understanding of who Jesus is (John 15:26) and why we need Him (John 16:7–11), a change in character (Galatians 5:22–23), and insight into the Scriptures (John 16:12–13). The culmination of all this change is that we will join in God's work of changing lives by teaching people about Jesus' gospel (Matthew 28:19–20).
In Scripture, "ripe grain" refers to a situation that has come to full fruition. In Joel 3:13, the "ripe harvest" is the full measure of evil God can stand before He destroys the nations. In the New Testament, ripe grain typically denotes new God-followers. The harvest refers to the end times when Jesus will come and take His followers from the corrupted world.
Although Mark 4 seems to infer that people who reject Jesus' message will be geographically separated and free to live as they choose, Matthew 13:24–30 adds detail to Mark's account. It says that once the seeds are sown, an enemy comes along behind and plants weeds in the field. This represents Satan putting various temptations and barriers in our path, designed to keep us from accepting and growing in Christ. Jesus warns that following Him may lead to split families (Luke 12:53) or even the necessity of distancing oneself from family (Mark 3:31–35).
This does not mean that a believer must categorically and completely separate from a family member who doesn't follow Christ or who causes issues. Jesus teaches that we should value reconciliation (Matthew 5:23–26), bear insults with grace (Matthew 5:38–40), and love those who persecute us (Matthew 5:43–48). This love is to be patient, kind, forbearing, and hopeful (1 Corinthians 13:4–7). God will not remove troublesome people from His followers until the end times. To separate believers now would remove Christian influence from the world. Christians cannot follow the command to spread Jesus' words if we're never around anyone who hasn't already heard them!