If the law didn’t exist today, after the cross, then nobody could ever sin.

Romans 4:15
“… FOR WHERE NO LAW IS,
there is no transgression.”

The first part of Romans 4:15 gives another way to prove the laws of God not only still exist but also still carry the penalty for breaking it as well “the wages of sin is death”.

Romans 4:15
“Because the law worketh wrath…”

Romans 1:18-19
“For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness; Because that which may be known of God is manifest in them; for God hath shewed it unto them.”

Who would know and hold (have) God’s truth? Would this be a believer or an unbeliever who doesn’t know God? Who has had God’s truth manifested within them (by the Holy Spirit)? Would this apply to a believer or an unbeliever?

When we seek God daily through confession and repentance like our example given to us in the Lord’s Prayer, we are acting by faith and we are forgiven if we’ve come humbly and sincerely. When God forgives our past sin, then we are no longer under the law of “the wages of sin is death” because Jesus Christ has cleansed, erased and taken away those sins forever.

Romans 6:22-23
“But now being made free from sin, and become servants to God, ye have your fruit unto holiness, and the end everlasting life. For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.”

Romans 6:15-16
“What then? shall we sin, because we are not under the law, but under grace? God forbid. Know ye not, that to whom ye yield yourselves servants to obey, his servants ye are to whom ye obey; WHETHER OF SIN UNTO DEATH, or of obedience unto righteousness?”

Paul isn’t saying that we as believers are not under any of God’s laws, he is specifically talking about “the wages of sin is death” law.

Romans 7:6
“But now we are delivered from the law,
THAT BEING DEAD
WHEREIN WE WERE HELD…”

How do we know that? Several ways, first because Paul who just said they weren’t under the law just told them in the next verse that if they turned back to serve sin, then they would die; the death penalty reapplies. Also if it was no longer possible for them to sin, he wouldn’t even warn them not to. That makes sense doesn’t it? Lastly again if the law didn’t exist and wasn’t binding, then there wouldn’t even be sin.

Romans 4:15
“… FOR WHERE NO LAW IS,
there is no transgression.”

The apostle Paul also said in 1 Corinthians 9:21:

“being not without law to God,
but under the law to Christ”

And making it even more clear, Paul warned us that even he himself could lose his salvation if he refused to obey God’s laws.

1Corinthians 9:27
“But I keep under my body, and bring it into subjection: lest that by any means, when I have preached to others, I myself should be a castaway.”