One True Gospel in a Sea of False...

Acts 2:31-39 (emphases mine):

[David] foresaw and spoke about the resurrection of the Christ, that he was not abandoned to Hades, nor did his flesh see corruption. This Jesus God raised up, and of that we are all witnesses. Being therefore exalted at the right hand of God, and having received from the Father the promise of the Holy Spirit, he has poured out this that you yourselves are seeing and hearing. For David did not ascend into the heavens, but he himself says, 'The Lord said to my Lord, sit at my right hand, until I make your enemies your footstool.' Let all the house of Israel therefore know for certain that God has made him both Lord and Christ, this Jesus whom you crucified. 

Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, "Brothers, what shall we do?" And Peter said to them, "Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the the gift of the Holy Spirit. For the promise is for you and for your children and for all who are far off,  everyone whom the Lord our God calls to Himself."

 With every week that passes, I discover yet another area in which the true, biblical gospel has been undermined. Whether among my peers at university through the teachings of professors or prominent liberal and post-modern theologians, or through common, even prevailing, modern-day versions of the gospel which leave out the most basic requirements of salvation according to the Bible.

Furthermore, with every week that passes, I become more enamored with the examples of men like Charles Spurgeon, John Calvin, and above all Martin Luther, men who declared war on false gospels and preached the true gospel with such fervor - men who were not hindered by niceness or propriety in their attacks on the false gospels and false preachers which poison Christian thinking.

So here, rather than try to answer every single false gospel, which is an impossible task, I will simply affirm the true gospel as I find it in the Scriptures. And, unless convicted by Scripture and plain reason that I am wrong, I will stand with the likes of Spurgeon, Calvin and Luther and declare war on any and all gospels which oppose, deny, or contradict these teachings.

Above, I quote Acts 2 with several phrases emphasized. I want to take each of those phrases in order to make a few key points:

1. Whom you crucified - Peter has just finished preaching to a large Jewish crowd on the Day of Pentecost. He has recited the prophecy of Joel concerning the "last days", and told the people that Jesus Christ has fulfilled it. Then, after asserting that Jesus Christ is the long-expected Messiah, he then turns to the crowd and tells them that they have crucified this Messiah. "You have spent your lives waiting for the Christ. I tell you now that he has appeared - and you killed Him!" Ouch. This is where the gospel begins - with an assertion of human sin - and not as a means to another end - that is, we don't teach that we need Jesus to improve our lives, but sin stands in the way. No, sin is the one and only problem which a gospel preacher need address. 
2. Cut to the heart - the response of the crowd is to be cut to the heart, caught under the crushing weight of their sin. How could they not? They killed the very one they had been waiting for. How could they escape the judgment of God? This is their motivation to become Christians. 
3. What shall we do?  - so they ask the Apostles what they have to do to escape the judgment of God. Their question is the one which I want to answer - "What shall we do to be saved?" Or, even simpler, "How do we become Christians?" 
4. Repent... - Peter gives two commands to them. The first is to repent. Even as they are crushed under the weight of their sin and the righteous judgment of God, they are commanded to repent - to turn from sin, to plead mercy, just like the tax collector in the temple, beating his chest and saying, "God, have mercy on me, a sinner!" (Luke 18:13).
5. ...and Be Baptized. - Interesting. What immediately follows repentance in Peter's admonition? Not "believe". Not "ask Jesus into your heart". Not "pray this prayer after me". Peter commands them to be baptized. I won't belabor the point at this juncture, as it is a matter of further study for me at the moment, but evidently, in preaching the gospel one also preaches baptism - Peter gave the command to be baptized before they had become Christians, in the same breath as "Repent", which is how you become a Christian. 
6. Everyone whom the Lord our God calls to Himself - The promise is not for everyone, but everyone who believes, whom God calls to himself. Notice the limitation of the last phrase - everyone whom the Lord our God calls. Implication - those who do not respond have not been called. That is, the call of the gospel is not to "believe that Jesus died for you". The gospel is, "Jesus died to save all those who believe. Therefore, believe!" The promise of the gospel is offered to all, but it is not for all - it is only for those who believe, who have been called. Furthermore, notice whose prerogative is the focus - everyone whom God calls. God is the one who calls. Salvation is the Lord and of His will - not human free will. An appeal to the free will of humans has no place in the preaching of the gospel. To preach the gospel is to preach the doctrines of grace, and of human inability. It is the sufficiency of Christ to save, and not the sincerity of human response to Him, which works salvation. 

The call of the gospel is to Repent and Believe. A gospel presentation which says different than this is not scriptural. May God unify his Church under one banner - the gospel of Jesus Christ.