Belief in Christ in 551 BC

Jacob 1:8; “Wherefore, we would to God that we could persuade all men not to rebel against God, to provoke him to anger, but that all men would believe in Christ, and view his death, and suffer his cross and bear the shame of the world; wherefore, I, Jacob, take it upon me to fulfil the commandment of my brother Nephi.” – 551 BC

Romans 1:30-32; “Backbiters, haters of God, despiteful, proud, boasters, inventors of evil things, disobedient to parents, 31 Without understanding, covenantbreakers, without natural affection, implacable, unmerciful: 32 Who knowing the judgment of God, that they which commit such things are worthy of death, not only do the same, but have pleasure in them that do them.”

Using this passage from Romans may seem rather random for this setting, but I feel the adjectives used fit their description and I want to bring to light the meaning of the word covenantbreakers. 

The word covenantbreakers in the Greek is asunthetos. It’s a negative particle from the word Alpha in the sense of a union and means properly not agreed with and/or treacherous to compacts.

This word is used only once in the New Testament and speaks of those who are absolutely irreconcilable and who will not be atoned.  It is those who’ve absolutely refused to abide by the covenants and treaties they’re in covenant with. (See Trench & Vine’s Expository)  

Now, what’s my point in using this passage? Because of what it says in Jacob 1:8.  Notice what he says here.  It is 551 BC and they’re using phrases like “suffer his cross” and “take it upon me to fulfill the commandment of my brother Nephi”… 

If the Jesus Christ we as Christians know and love and are in a covenant relationship with wasn’t born until circa 00 AD, then who is this character they’re referring to in 551 BC? And why is he talking about a cross? These things can only be referring to another Christ and another Jesus whom God does not recognize as His Son. 

Lastly, why is he fulfilling the commandments of his brother? What about fulfilling the commandments of God and staying put in Jerusalem like God told the Israelites to do? (Jer. 42:15-19)