Now, tell us exactly how and for what reason that's a false Gospel.
We could examine each of the Five Points of Calvinism to establish this. But let's take the teaching that goes to the heart of the Gospel -- Limited Atonement. The true Gospel presents Unlimited Atonement -- that Christ died for the sins of THE WHOLE WORLD, therefore
all may be saved if all will repent and believe on the Lord Jesus Christ.
Let's assume you were preaching the Gospel to a crowd of 100 unsaved people. According to your Gospel, you could not -- in good conscience -- say to this crowd:
"There is not a single person here who cannot be saved by the grace of God today".
Why? Because you believe that (a) God will elect only some for salvation, (b) Christ did not die for the sins of the whole world, but only for the elect, (c) therefore God selectively gives saving faith to some (as a gift), and ignores others.
On the other hand Christ and the apostles would be able to make that declaration based upon what they have received from God -- which is Unlimited Atonement for "whosoever" will repent and believe on the Lord Jesus Christ. Since I have already posted the Scriptures which teach Unlimited Atonement, let's just focus on how, and on what basis, the Gospel was preached in Scripture.
EVERY PERSON MUST HEAR THE GOSPEL BECAUSE ALL MAY BE SAVED
And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth.Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen. (Mt 28:18-20)
And he said unto them, Go ye into all the world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be damned. (Mk 16:15,16)
And [Christ] said unto them, Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day:And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem. And ye are witnesses of these things. And, behold, I send the promise of my Father upon you: but tarry ye in the city of Jerusalem, until ye be endued with power from on high. (Lk 24:46-49)
And he said unto them, It is not for you to know the times or the seasons, which the Father hath put in his own power. But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth. (Acts 1:7,8)
And the times of this ignorance God winked at; but now commandeth all men every where to repent: Because he hath appointed a day, in the which he will judge the world in righteousness by that man whom he hath ordained; whereof he hath given assurance unto all men, in that he hath raised him from the dead. (Acts 17:30,31)
Now, the underlying premises in all these passages are that (1) the Gospel is the power of God unto salvation, and it is the Gospel, under the power of the Holy Spirit, that generates faith in the unsaved; (2) Christ died for the sins of the whole world; (3) therefore all men everywhere are commanded to obey the Gospel; (4) that God has given assurance to all men through the Gospel that Jesus Christ is the Savior of the world through His death, burial, and resurrection; (5) therefore all men may be saved if all will repent and believe.
But what does Calvinism do? IT REJECTS ALL OF THESE FUNDAMENTAL GOSPEL PREMISES and comes up with "another gospel".