How Do They Know?

Once again, the Calvinists making the mistake of applying God's choice to grant something nationally to their doctrine of individual election.

If the Baptist Board Admins announced they were changing the name to "Whosoever Board" and were now granting admission to Catholics would all Calvinists naturally assume that the Admins were individually selecting which Catholic would or wouldn't be admitted to the neglect of all others? Or could they read the announcement like a normal person and conclude that the BB was merely allowing any Catholic who wanted to join to be admitted?

 

No more than Antinomianism is the logical outgrowth of the sovereign grace doctrines.
Both statements are assumed 'the logical outgrowth of' due to willful ignorance.

 

Acts 11:13 And he shewed us how he had seen an angel in his house, which stood and said unto him, Send men to Joppa, and call for Simon, whose surname is Peter;
14 Who shall tell thee words, whereby thou and all thy house shall be saved.
15 And as I began to speak, the Holy Ghost fell on them, as on us at the beginning.
16 Then remembered I the word of the Lord, how that he said, John indeed baptized with water; but ye shall be baptized with the Holy Ghost.
17 Forasmuch then as God gave them the like gift as he did unto us, who believed on the Lord Jesus Christ; what was I, that I could withstand God?
18 When they heard these things, they held their peace, and glorified God, saying, Then hath God also to the Gentiles granted repentance unto life.

The topic here is the gospel. Notice in verse 14 it says "Who shall tell thee words, whereby thou and all thy house shall be saved". These words are the gospel.

Notice in verse 17 that the Holy Ghost was given to those who believed on Jesus. So, once again we see the order always seen in scripture, #1 hear the word of God, #2 believe the word of God, #3 receive the Holy Spirit.

Verse 18 is saying that God had sent the gospel to the Gentiles. This is shown repeatedly in the book of Acts. As DHK said, you have to repent and believe to be saved. The Gentiles could not have been saved as they did not have the gospel to this point. Peter is just saying that now the gospel has been sent out to the Gentiles and so they are able to repent/believe on Jesus unto life.

Acts 28:28 Be it known therefore unto you, that the salvation of God is sent unto the Gentiles, and that they will hear it.

The "it" in this verse is the gospel. But a person could twist this verse and focus on "the salvation of God is sent unto the Gentiles" as though salvation is imposed on a man. That is what Calvinists are trying to do with Acts 11:18. Just as here it is the gospel that is being spoken of.

It is the gospel that went to the Gentiles. And if they hear it and believe it they receive life just as the Jews had.