What is the apostology?

A church which does not have any missionary activity or work is a dead church. Church exists in the world with a mission. A mission to proclaim the Gospel of Christ Jesus who died and resurrected from the dead. A mission to go as well as to send missionaries to other parts of the world where people do not even hear the name Jesus Christ in their whole life. There are many parts of the world where nations and people groups are not yet reached with the Gospel of Christ Jesus. There are many places in the world, where the existing Christian churches need teachers, leaders, and missionaries to teach, to disciple, and to train them. There are many Christians who not only need prayers but also financial and material supports to survive for life. Pastors, how many churches do your church financially support today? How many missionaries do your church organization send to other parts of the world? Are you a mission minded pastors or Christians? Historically, missiologists have been discussed on the significance of "sending" or "to send" missionaries to foreign countries and nations to evangelize, to teach, to share, to preach, to train, and do other missionary works for the kingdom of God. Why is this "sending" so importance for the missions of the Christian church? The famous missiologist Gustav Warneck (1834-1910), the father of mission science, who taught in Halle, Germany, in the late nineteenth century have proposed four alternative categories for missiology. They are 1) halieutics (to fish or fisherman), 2) kerytics (to preach or to herald), 3) evangelistics (evangelist is one of the office of ministries in the church), and 4) apostology (to send). Gustav Warneck has drawn all these four areas of mission activities from the various biblical references in the Bible. The Lord Jesus Christ and Saint Paul have used all these four terms during their missionary works. Among these four terms, apostology, according to Detlve K. Schulz, can be found 131 times in the New Testament. Jesus Christ was the sent One. God the Father sent the Son, Jesus Christ, to proclaim the kingdom of God and die for humanity on the cross so that whoever believes in Jesus Christ by the Holy Spirit will receive the eternal life in heaven. God the Father sent the Son, the Father and the Son sent the Holy Spirit send the church to the lost world. Missio Dei is God doing redemptive works through the church in the world. Thus, "to send" or "sending" missionaries to other nations or people groups is significant and essential for Christian missions. Paul encourages in his writing saying that "how are they to preach unless they are sent" (Rom.10:15). Jesus said "peace be with you! As the Father has sent me, I am sending you." (John 20:21) Before He was taken up to heaven, Jesus Christ said to His disciples, "But you will receive power when the Holy Spirit comes on you, and you will be my witnesses in Jerusalem, and in all Judea, and Samaria, and to the end of the earth." (Acts 1:8) The Lord Jesus Christ wants us to be His witnesses not only in our own cities or countries, but also to the other parts of the world. He wants us to go and make disciples of all nations by baptizing them in the name of the Father and of the Son, and of the Holy, teaching them to observe everything He has commanded us to do for He promises us to be with us to the very end of the age. (Matthew 28: 19)