No one has made the claim Paul was referring to the Mosaic Law in every instance--only that (1) Paul differentiated between certain rituals of the Mosaic Law--and obedience to the gospel--and (2) Paul often was referring to the rituals under the Mosaic Law when referring to works, and/or that it was God's grace which brought man back to eternal life--not their obedience to God.
1 Corinthians 7:19---King James Version
19 Circumcision is nothing, and uncircumcision is nothing, but the keeping of the commandments of God.
Romans 5:18---King James Version
18 Therefore as by the offence of one judgment came upon all men to condemnation; even so by the righteousness of one the free gift came upon all men unto justification of life.
In no place did Paul disassociate keeping the commandments with His grace unto eternal life:
1 Corinthians 6:9-10---King James Version
9 Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind,
10 Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God.
IOW--although eternal life had it's origins in God's grace alone, not our obedience, faith, endurance, belief, etc.--He only extends that grace to those who obey His commandments.(faith in Christ)
How do you collate your theology with the posted scriptures?