The FINISHED GOSPEL: An End Time Discernment Priority  — THE GOSPEL TO ALL NATIONS
Jesus gave us Revelation as the capstone book of prophecy and the Bible. He framed Revelation with the free Gospel of grace (1:5, 22:17). He called that Gospel the "Everlasting Gospel" (14:6), and designated it as perhaps the greatest sign of the End Time (Mat. 24:14; Mark 13:10).     

        "And this gospel of the kingdom shall be preached in the whole world for a witness to all the nations, and then the end shall come” (Matthew 24:14).     

        "And the gospel1 must first be preached to all the nations (Mark 13:10).2
To preach the whole "gospel of the kingdom" (Mat. 24:14) is to preach the Gospel of Salvation (Mark 13:10), for you cannot "enter into the kingdom of God" apart from the Gospel of Salvation (John 3:3-5). Therefore, since the Gospel must "be preached in the whole world" BEFORE "the end shall come”, both Matthew 24:14 and Mark 13:10 establish the Gospel as a premier sign of End Time Prophecy. And since it must be the correct Gospel of Salvation to be the correct Gospel of the Kingdom, to preach any other gospel does not fulfill that sign.
Furthermore, the Gospel is the ultimate personal-prophecy, since it prophecies a destiny of Heaven or Hell for every person based on their acceptance or rejection of the free gift of salvation in Jesus Christ.
Discernment of the correct Gospel is literally a matter of life or death. This makes the Gospel3  the priority sign of Bible Prophecy. For example,

            1. I may know all about the prophecies of End-Time Israel, but if my faith is not in the correct Gospel, then I will enter the End-Time Tribulation.    

            2. I may know all about the Rapture prophecies, but if my faith is not in the correct Gospel, then I will be left behind at the Rapture.   

            3. I may know all about the Resurrection prophecies, but if my faith is not in the correct Gospel, then I will be in the Resurrection of Judgment.   

            4. I may know all about the prophecies of the Coming Kingdom of Christ, but if my faith is not in the correct Gospel, then I will be excluded from that                 Kingdom.

Serious indeed! Why? Because there is more than one gospel in Christianity. But there is only one true Gospel. The distinguishing mark of the true Gospel is that it's saving-work was "finished" at the cross by Jesus Christ. The distinguishing mark of a "contrary" gospel (Gal. 1:6-9) is that it is "unfinished", requiring the additional work of man.

The true Gospel has accurately been described as salvation by Grace Alone, through Faith Alone, in Christ Alone. The "contrary" gospel seems to agree with the three "Alone" statements — until it adds Works — at which point the "Alone" concept is destroyed in all three of its applications (Grace Alone, Faith Alone, Christ Alone). The very moment the Works of man is introduced, the Finished Gospel of Christ is replaced by the Unfinished Gospel, that is, the "different, distorted, contrary" gospel Paul strongly condemned in Galatians 1:6-9.

Discernment of the difference between the Finished Gospel and the Unfinished Gospel should be a supreme issue in Bible Prophecy.

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