Claim: After Paul received the supposed revelation, he went out to teach to the Gentiles, implying the revelation was for the Gentiles or can be preached to the Gentiles.
Problem: The problem arises when we see that in Galatians and Acts, two different accounts exist as to which people that the message was revealed for:
Galatians 1:16: To reveal his Son in me, that I might preach him among the heathen; immediately I conferred not with flesh and blood:
Galations 2:7 But contrariwise, when they saw that the gospel of the uncircumcision was committed unto me, as the gospel of the circumcision was unto Peter;
So as we can see, in Galatians after receiving the revelation Paul jumped and started preaching to the gentiles, hence the revelation was for the Gentiles.
Now lets see what Acts says:
Acts 9:20: And straightway he preached Christ in the synagogues, that he is the Son of God.
Acts 13:5: And when they were at Salamis, they preached the word of God in the synagogues of the Jews: and they had also John to their minister.
Acts 13:14: But when they departed from Perga, they came to Antioch in Pisidia, and went into the synagogue on the sabbath day, and sat down.
Acts 14:1 And it came to pass in Iconium, that they went both together into the synagogue of the Jews, and so spake, that a great multitude both of the Jews and also of the Greeks believed.
So essentially, we see two problems.
One, these are two contradictory accounts. We see in Galatians that Paul, after receiving revelation, went and started preaching to the Gentiles. Whereas in Acts, after receiving revelation he went and started preaching to the Jews and when they rejected him, only then did he went to the Gentiles.
Secondly, it seems obvious that Paul had wanted to preach to the Jews, and the revelations he allegedly received were for the Jews. Furthermore, they rejected him as an imposter and a liar, because they knew their own scriptures and hence they knew that Paul was nothing more than an imposter.