Note that this question is actually multi-faceted. We must not only consider what the direct impact is upon the harvest of souls, but how it effects the size of the harvest. First of all, it is important to recognize that there is a direct correlation between the announcement of God's Kingdom and the Gospel of the Kingdom. It should go without saying that both are announcing the "Good News" that God's Kingdom (the actual realm where He resides) has now made itself known here on earth. This announcement would soon make the Kingdom a reality; becoming apparent by the evidence shown in Jesus's life. And Jesus would inaugurate the Kingdom message when He began His ministry, preaching "Repent, for the Kingdom of Heaven is at hand".
The good news of this Gospel Message about God's Kingdom coming to earth is that mankind now had a way to be acceptable before God. Prior to Jesus's appearance, man had lived in a state of hopelessness due to how God viewed sin. The Bible makes His holy opinion easy to understand: The soul who sins shall die (Ezekiel 18:20). But with the arrival of Jesus, mankind now had a Savior who would provide a way out of experiencing eternal death, which was the consequence for our sins against a Holy God.
All the prophets had foretold of this Savior that would take away the sins of the world and restore man's relationship with God as it had been in the Garden of Eden. Remember: God's Kingdom is where God resides; the realm in which He rules. Between the time man fell into sin in the Garden and the time of this announcement, that kingdom realm had existed only in Heaven. Now, here comes John the Baptist foretelling that this Kingdom is near, rapidly followed by Jesus's appearance and the beginning of His ministry to announce that God's Kingdom was now here! So it's not too difficult to see the immense impact that this announcement would have on God's harvest of souls.
No longer would man be subject to Laws that were incapable of delivering us from Death. But man would now be able to stand before God in righteousness through believing in the sacrifice He would make of Himself [as His Son, Jesus Christ] on our behalf. By following Jesus's example of living according to the Father's will, the impact on the harvest would become nothing short of miraculous and astounding. Those who would accept and respond to His announcement and ministry would begin to change the world. The realm of Satan here on the earth would come into direct conflict with the people who walked in their authority as members of God's Kingdom on earth. The number of citizens of Satan's kingdom would diminish, as the number of citizens of God's Kingdom rose.
That was the plan! But if we are going to resemble Christ's image [and His work] here on earth, then we have to announce more than the deliverance from eternal Death; although, that in itself is worthy of our acclamation and enthusiastic approval. You see, that deliverance isn't realized until the end of our life. So, while that good news of our salvation from Death is responsible for a magnificent number coming into the harvest, I believe we gain staggering numbers when we reveal ALL of the good news that the announcement of the Kingdom generates.
Think about it: a person recognizes their need of a Savior and accepts Jesus into their heart, repenting for their sins and asking forgiveness. Is that news worthy of sharing? Absolutely! But if the newly saved Christian takes that message to the person who sees the penalty of sin [and their resulting death] as a far-off event, the message may have no immediate relevance. But let's say that we add to that message of salvation. Let's say we share that the reality of the Kingdom of God being present today ALSO gives you access to the power of the Holy Spirit to heal persistent physical/health problems, or to set one free from the bondage of shame, guilt, anger, and unforgiveness, to name just a few of the attacks from the devil. Can you see that we now offer an immediate benefit from our announcement of the Kingdom at hand? Can you perceive that this full Gospel message of the Kingdom might result in a greater number in the harvest -- in other words, the impact on the size of the harvest might be more considerable if we share the complete picture of the Kingdom of God, on earth as it is in heaven. It is more than salvation [as magnificent as that is]; it is freedom; it is power; it is authority to battle in the spiritual realms as God leads us.
Who doesn't have a health issue they are dealing with in these perishable bodies? It doesn't matter if it is a simple headache or stage 4 cancer. We want it to go away! And I defy us to find anyone within the Body of Christ who has not suffered at least one attack or violation from the Enemy on their character, their identity, their relationships with others, or the privacy of their body. We may know Jesus as our Savior and rely on our ultimate deliverance from Death, but who wouldn't want to be liberated from the oppressive thoughts and emotions that we carry around with us because of these assaults on our spirits and flesh? What would happen if Christians could praise Jesus for how He healed them from sexual molestation; loss of self-respect and self-esteem; bullying; abusive parents; or promiscuity and drug/alcohol abuse? Do you think more people would identify with those victories -- or a victory over their future death?
I'm not saying that the good news of our salvation from eternal death is not an important message to share... it's the ultimate reward! But there is more to Jesus's victory and what that victory looks like in the here-and-now. I am so grateful that the Holy Spirit has revealed to my heart the need of my Savior. I look forward to my glorious resurrection and dwelling forever with the Lord when the new Heaven and new Earth appear. But I am equally grateful that He has set me free NOW to praise Him for delivering me from the bad choices I have made in my life; from the attempts of the devil to kill, steal, and destroy this Kingdom life in the present; and for giving me the opportunity to share this restored life, made in His image.
It is my responsibility [and my joy] as the recipient of Jesus's authority and the power of the Holy Spirit to invite others to partake of God's goodness to those who believe in Him. When we share all that we have received from Heaven's invasion of earth, then we can expect to see an impact of righteousness and growing numbers of ambassadors. And, Lord knows, we need more Heaven on earth today! The growing trend towards lawlessness, in all its aspects, needs a response from Heaven's citizens on earth. And it must happen in more than words; let your faith become action! Walk in your power and authority to heal, defeat demons, and set the captives free. Let us increase the harvest a hundred-fold! Let the "Good News of the Kingdom" be realized across the face of this planet, and let all the people shout "Hallelujah!" as our voices join in worship, praise and rejoicing as the we participate in bringing in God's harvest.
Matthew 9:38 "The harvest is plentiful, but the laborers are few; Therefore pray earnestly to the Lord of the harvest to send out laborers into His harvest".