DISOBEY THE GOSPEL = DISBELIEVE IN IT
Brad McCoy states, ('The Grace Evangelical Society News,' Sep-Oct '94 issue, 'Obedience Is Necessary To Receive Eternal Life', p. 3)
"When one hears the Gospel and is challenged to believe in Christ, but for whatever reason does not, he has in fact disobeyed the call to believe!"
[Compare: Acts 14:1-2]:
(v. 1) "At Iconium Paul and Barnabas went as usual into the Jewish synagogue. There they spoke so effectively that a great number of Jews and Gentiles believed.
(v. 2) But the Jews who refused to believe stirred up the Gentiles and poisoned their minds against the brothers."
"Jews who refused to believe" = "apeithountes Ioudaioi" = literally translated: "disobeying Jews" which is best rendered in English: "Jews who refused to believe"
[Compare 1 Pet 2:7]:
"Now to you who believe, this stone [Christ, the Cornerstone] is precious. But to those who do not believe..."
"But to those who do not believe..." = "apedokimasan" = literally: "to [those] disobeying"
(Cp 1 Pet 4:17; Acts 5:32; 6:7)
...The call of the Gospel is to believe on the Lord Jesus Christ (Acts 16:30-31; 1 John 5:1). When one hears this call and believes, he has obeyed the Gospel. In that sense, then, his faith is an act of obedience.."
[Compare 2 Thes 1:8]:
"He will punish those who do not know God, that is to say, who do not obey the gospel of our Lord Jesus."
["that is to say" = "kai"]
(v. 1) Therefore [Christians] be imitators of God, as beloved children [believers];
["Therefore, be imitators.." = Paul is commanding Christians in this passage, (Eph 14:1b - 3; 13:30-32), who are eternally secure, (Eph 4:30; Jn 10:28) to be imitators of God]
(v. 2) and walk in love, just as Christ also loved you, and gave Himself up for us, an offering and a sacrifice to God as a fragrant aroma.
(v. 3) But do not let immorality or any impurity or greed even be named among you, as is proper among saints;
[Notice that Paul indicates the proper behavior for saints: moral, righteous behavior - as opposed to improper behavior: "immorality," and "impurity" and "greed." This strongly implies that saints can behave improperly and still be called saints, i.e., still have eternal life]
(v. 4) and there must be no filthiness and silly talk, or coarse jesting, which are not fitting, but rather giving of thanks.
(v. 5) For this you know with certainty, that no immoral or impure person or covetous man, or one who is an idolator, has an inheritance in the kingdom of Christ, even God.
["...Christ, even God" = "...Christ, Who I mean to say is God". When occurs in this manner, i.e., when the noun after it, is without an article; it signifies identification of this noun "God") with the first noun "Christ".
"has an inheritance" = a disobedient believer will not receive an inheritance of any kind when that child of God, (Eph 5:1), goes to heaven. That child has been disinherited but remains a saved child who will go to heaven but with precious few rewards and inheritance, (Eph 4:30; I Cor 3:11-15).
(v. 6) Let no one deceive you with empty words, for because of these things the wrath of God comes upon the sons of disobedience"
"sons of disobedience" = those who disobey the gospel, i.e., those who do not believe in Christ as Savior, are defined as sons of disobedience, i.e., sons of Satan, unbelievers. The only requirement of the Gospel is to believe it, (Jn 3:16; Eph 2:8-9). So
to DISobey the gospel can only mean to DISbelieve in it. Compare I Pet 1:18-22, 2:6-8. I Pet 4:17 teaches that to obey the gospel is to believe it, to disobey the gospel is to disbelieve it. Compare Eph 2:1-3 ? unbelievers are disobedient & follow Satan.
Compare Jn 3:36 which contains the Greek word rendered "disobedient" = refusing to believe in the Son:
"Whoever believes in the Son has eternal life, but whoever refuses to believe and obey, i.e., rejects the Son [as his Savior] will not see life, for God's wrath remains on him."
"Whoever believes in Him is not condemned, but whoever does not believe stands condemned already because he has not believed in the name of God's one and only Son."
Notice that here in John 3:18 that the only condition presented for being condemned is to not believe in the name of God's one and only Son. Compare Jn 8:42-47 = those who do not believe in Christ belong to their father the devil, i.e., are not saved.
Since the sole condition on the part of the individual is to receive eternal life is to trust alone in Christ alone
since the sole condition of condemnation unto the Lake of Fire, i.e., since the only thing that gets you condemned to hell is not ever trusting alone in Christ alone as Savior
since disobeying the gospel of salvation gets you condemned to hell then disobeying the gospel of salvation is the same thing as disbelieving it. One can disobey by doing something 'out of the line of the authority that you are under' and one can also disobey by believing something out of line.