The famous verse by Paul in Romans 1:16 says, “ For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek.”
In other words the Gospel of the person and work of Jesus Christ is what saves souls. All souls, from every tribe, nation and tongue (Rev. 14:6) are saved by the Gospel.
In the tremendous scene in Revelation 5 of the worship of God on His throne the one Person in the midst of the scene is the Lamb of God. There is no one like Him.
Read this attesting to His singular power to save Rev. 5:9-14:
9 And they *sang a new song, saying, “Worthy are You to take the book and to break its seals; for You were slain, and purchased for God with Your blood men from every tribe and tongue and people and nation. 10 “You have made them to be a kingdom and priests to our God; and they will reign upon the earth.”
11 Then I looked, and I heard the voice of many angels around the throne and the living creatures and the elders; and the number of them was myriads of myriads, and thousands of thousands, 12 saying with a loud voice, “Worthy is the Lamb that was slain to receive power and riches and wisdom and might and honor and glory and blessing.”
13 And every created thing which is in heaven and on the earth and under the earth and on the sea, and all things in them, I heard saying, “To Him who sits on the throne, and to the Lamb, be blessing and honor and glory and dominion forever and ever.”
14 And the four living creatures kept saying, “Amen.” And the elders fell down and worshiped. The world is telling us that you have to have a week to the Gospel for each people group and in the in our day the Gospel doesn’t work on modern man.
If you want souls to be saved the power for their salvation is the Gospel of Jesus Christ. Jesus Himself the gates of hell will not prevail against the Gospel (Matt 16:18).
This means you can go anywhere anytime and depend upon the Gospel to save. So preach IT in season and out.