LOL! That's a good example.
If the Gospel we preach and by which we are saved now of necessity includes the Death, Burial, and Resurrection of Christ (1 Cor. 15:1-4), then the Gospel that the Twelve and the Seventy were commissioned to preach during Christ's earthly ministry (Matthew 10; Luke 9, 10) had to be a different message, because they did not understand the sufferings of Christ.
Yes, that makes sense. However, while that message may not have been as developed as the one we have today, I would doubt that it contained error. (I know you didn't say that.)
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Right. The message the Apostles and the Seventy preach was the correct message; nothing at all erroneous. It was the Gospel of the Kingdom of Heaven — that the KING was now present and that His Kingdom was “at hand.” It was the message of the “consolation” of Israel that was long-awaited by many in Jerusalem (Simeon, Anna, likely Mary and Joseph, and Elisabeth, and Andrew, etc. etc. etc.)
They were awaiting and expecting the long-prophesied DAVIDIC Kingdom with Messiah reigning on earth. This was STILL the burden of the message AFTER the Resurrection of Christ and His Ascension. You will find it throughout Acts chs. 2, 3, 6, 7.