All I can say anyone who understands the concept of justification and grace as taught by Paul would never make such a ridiculous statement.
It is completely absurd, like some how a person will flourish by adopting a sinful lifestyle.
Exactly what Paul warned about, here it is again. Let it really sink in.
And why not say, “Let us do evil that good may come”?—as we are slanderously reported and as some affirm that we say.
Their condemnation is just.
Roman 3:8
Do you really believe all sins were paid for at the cross?
Yes, I agree that those who are in Christ know he is Lord. We also know as you said the idea that our state of justification and eternal salvation through God's grace gives us a license to sin is not only absurd, but in my view is evidence those who make the argument do not know Jesus is Lord.
Otherwise they wouldn't deny his work on the cross that sealed his gospel. And the very reason he was born.
Those who make the sin assertion you may notice totally ignore all the passages in the Bible and posted here too that inform us those in Christ do not believe they can sin with impunity.
Therefore the assertion that OSAS gives license to sin actually is a slander on their part against God. Because God sent his only begotten son to bring the eternal life,salvation, covenant to the world by his grace alone.
Then I think the question comes as a turn about on them.
Why,in God's Holy name would anyone who does know Jesus is Lord, insist he died to give those of us in God's grace a license to sin? If they claim to be saved by the same Jesus and gospel ?
Seems adverse to the entirety of the New Testament doesn't it?
Jesus' blood sealed the new covenant not as an offer of salvation but as evidence of our Lord's sacrifice and work on the cross as his eternal accomplishment of salvation in the hearts of God’s people.Jesus gives rebirth,redemption,justification through our Lord's power to do so based on his work in bringing the gospel to this world.
We have been reborn from that dead in our sins carnal natural minded fallen state we were born into. We now have a new heart, and spirit.
All is by the grace of God, not our work or choice. It is God through Jesus' sacrificial work on the cross that blesses us with his gift of life, faith,
and obedience.
Romans 8:32 “He who did not spare his own Son, but gave him up for us all”
“This cup that is poured out for you is the new covenant in my blood.” Luke 22:20