You are contradicting yourself.
If there "is a single theology and a single soteriology which is intended for everyone including all Jews and Gentiles, which is believed by every child of God who ever lived,
then there is no need to divide anything at all in scripture.
"Rightly dividing" doesn't mean dividing up truth into contrary truths for different people. What you are dividing is the Body of Christ, which Paul reprimanded the Corinthians for. "Dividing" is an antiquated way of saying "straight down the line." It doesn't mean "divide" as you are using it. To help, here are other translations of that verse:
NLT: Work hard so you can present yourself to God and receive his approval. Be a good worker, one who does not need to be ashamed and who correctly explains the word of truth.
NIV: Do your best to present yourself to God as one approved, a worker who does not need to be ashamed and who correctly handles the word of truth.
ESV: Do your best to present yourself to God as one approved, a worker who has no need to be ashamed, rightly handling the word of truth.
CSB: Be diligent to present yourself to God as one approved, a worker who doesn’t need to be ashamed, correctly teaching the word of truth.
NASB20: Be diligent to present yourself approved to God as a worker who does not need to be ashamed, accurately handling the word of truth.
NASB95: Be diligent to present yourself approved to God as a workman who does not need to be ashamed, accurately handling the word of truth.
LSB: Be diligent to present yourself approved to God as a workman who does not need to be ashamed, accurately handling the word of truth.
AMP: Study and do your best to present yourself to God approved, a workman [tested by trial] who has no reason to be ashamed, accurately handling and skillfully teaching the word of truth.
NET: Make every effort to present yourself before God as a proven worker who does not need to be ashamed, teaching the message of truth accurately.
RSV: Do your best to present yourself to God as one approved, a workman who has no need to be ashamed, rightly handling the word of truth.
Notice all the "accurate handling," "rightly handling," "correctly teaching," etc. ways they translate the Greek here. But the way you are using "divide," which is clear in your responses, is clearly wrong. It doesn't mean divide up soteriology into different gospels as you are doing. It means interpret scripture correctly.
I know that C.R. Stam taught the two-gospel scenario, which is heresy. Did you get the idea from him, or from someone else?