What is the gospel that Paul preached to unbelievers in Corinth? How did he explain it to them? What terminology did he use?
Thankfully we do not have to guess for he explicitly sets it out for us. He didn’t preach to them Christ died for some peoples sins, or that Christ died for the elects sins only, or that Christ may have died for some here. He preached it exactly like this to them: “Christ died for OUR sins”.
That’s what he explicitly states is part of the gospel that he preached to them in Corinth.
This would be impossible to preach to them should it merely be true that Jesus only died for some people and not for others. For it would be preaching something he couldn’t know is actually true!
Maybe Jesus didn’t die for some in the gathering! But Paul was happy to preach to the unbelievers in Corinth that Christ died for “our sins.” Paul believed and so preached that Jesus Christ died for all. And this is the gospel.
“Now I make known to you, brethren, the gospel which I preached to you, which also you received, in which also you stand, by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain. For I delivered to you as of first importance what I also received, that 𝐂𝐡𝐫𝐢𝐬𝐭 𝐃𝐢𝐞𝐝 𝐅𝐨𝐫 𝐎𝐮𝐫 𝐒𝐢𝐧𝐬 according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures,”
1 Corinthians 15:1-4