““No man will be able to stand before you all the days of your life. Just as I have been with Moses, I will be with you; I will not fail you or forsake you. “Be strong and courageous, for you shall cause this people to inherit the land which I swore to their fathers to give them. “Only be strong and very courageous to be careful to do according to all the law which Moses My servant commanded you; do not turn aside from it to the right or to the left, so that you may be prosperous wherever you go. “This book of the law shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it; for then you will make your way successful, and then you will be prosperous. “Have I not commanded you? Be strong and courageous! Do not be in dread or be dismayed, for Yahweh your God is with you wherever you go.”” (Joshua 1:5–9 LSB) https://accordance.bible/link/read/LSB#Josh._1:5
The church and the Great Commission are the New Testament version of Israel and the Promised Land. Israel was given a land; the church has been sent to the nations. No people could stand against Joshua and the gates of hell cannot stand against the church. As the nations would fall before Joshua so too principalities and powers in high places fall before the church as it proclaims the truth of God in Jesus the Savior. As Israel possessed the land so the church is to fill the lands with the knowledge of God in Jesus the Savior. As God was with Israel for success so too He has promised to never leave nor forsake His church but to empower His church for accomplishing His work through the Holy Spirit given to His people. As the people resisted Israel so too men will resist the gospel. As Israel was not to fear high walls and tall people, so the church must not fear men who oppose them, imprison them, or cause them harm for sharing the gospel of Jesus the Savior. The church is to courageously make known the work of God through the person of God in Jesus the Savior in the world God created. This is every Christian’s mission, their primary occupation using their vocation as their mission field and source for ministry funding. The reason the lands are not all Christian is because all Christians are not sharing the gospel of Jesus Christ across all the lands. We must engage, we must be courageous, we must be committed, we must be obedient, to the work of God, recorded in the word of God, for the glory of God.