Scott,
I would say that the scenario of evangelism you have described doesn't fit anything found in the Scriptures. Rather we find that:
1. All the gospels revolve around the assumption that Jesus is the Messiah promised in the Old Testament.
2. In Acts we find that when the gospel went out from Israel Jesus was presented to both Jew and Gentile as the Jewish Messiah.
In some instances (specifically Lystra and Athens) where there were people who apparently (though not certainly) had no knowledge of the Jewish religion, the emphasis turned to God as creator. However, I think we can fairly assume that had these men shown any interest in the message (as they did at Athens) Paul would have further instructed them into both the Messianic, lordship, and sacrificial character of Jesus.
3. All of the church letters, from Romans to Revelation, assume that the readers had an understanding that Jesus was the Christ. The message of Jesus was so tied to the Old Testament Scriptures that Paul both opened and closed his magnum opus with this thought:
"Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God, (which he had promised afore by his prophets in the holy scriptures."
And,
"Now to him that is of power to stablish you according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began, but now is made manifest, and by the scriptures of the prophets,according to the commandment of the everlasting God, made known to all nations for the obedience of faith: to God only wise be glory through Jesus Christ for ever. Amen."
4. The very words "Jesus Christ" mean nothing other than "Jesus Messiah" and therefore it is not possible to believe on "Jesus Christ" without believing He is the Messiah of the Jews.
5. Even if we were to accept your scenario of ignorant men accepting Jesus as "Lord" without any awareness of His Messianic character, that would have no bearing on the point of discussion which raised this issue - which point was that many modernists/liberals teach that the Old Testament did not promise a Messiah at all.
These men cannot plead ignorance. They know full well that the New Testament claims Jesus is the promised Messiah. They say they believe in "Jesus Christ."
And yet they assert (as do many modernist Jews) that the Old Testament never really promised a personal Messiah. They see the Old Testament as nothing more than a pack of Jewish fables. Such men, without question, fall into the condemnation decreed through the apostle John,
"Who is a liar but he that denieth that Jesus is the Christ? He is an anti-christ, that denieth the Father and the Son."
And as John also records in his gospel,
"And he said unto them, Ye are from beneath; I am from above: ye are of this world; I am not of this world. I said therefore unto you, that ye shall die in your sins; for if ye believe not that I am he, ye shall die in your sins. Then said they unto him, who are thou? And Jesus saith unto them, Even the same that I said unto you from the beginning."
Mark Osgatharp