There is a third option that you are missing. They are both speaking the truth, each to a different audience.
Again I ask then some what should be simple questions:
Why were these books written so late in the first century some even after 70AD if that different gospel that the apostles supposedly taught would end with the death of the apostles?
Unless of course there are still two gospels today...
Why would they(the apostles) still be teaching it even after Paul was shown the mystery of the new gospel?
How were the apostles saved?
How were those under the Law saved?
How were those before the law saved?
How were Gentiles before the law saved?
What was the point in the animal sacrifices? Please be as descriptive as possible.
Did those animal sacrifices bring about forgiveness? If not full forgiveness, what did they point to?
Do you believe anyone was ever saved by obeying the law? And you can't say Christ here, He was the only perfect one that fulfilled the law.