1 - We are ALL SINNERS.
"For all have sinned, and come short of the glory of God;"
Romans 3:23
"As it is written, There is none righteous, no, not one:"
Romans 3:10
2 - Use God's law (the SCHOOLMASTER) found in the book of Romans to explain what SIN is.
"...I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet." Romans 7:7
"Thou that preachest a man should not steal, dost thou steal? Thou that sayest a man should not commit adultery, dost thou commit adultery? thou that abhorrest idols, dost thou commit sacrilege?"
Romans 2:21-22
"Being filled with all unrighteousness, fornication, wickedness, covetousness, maliciousness; full of envy, murder, debate, deceit, malignity; whisperers, Backbiters, haters of God, despiteful, proud, boasters, inventors of evil things, disobedient to parents," Romans 1:29-30
3 - As a sinner we are under the curse of GOD'S LAW, and are condemned to JUDGMENT & DEATH.
"Now we know that what things soever the law saith, it saith to them who are under the law: that EVERY mouth may be stopped, and ALL THE WORLD MAY BECOME GUILTY BEFORE GOD." Romans 3:19
"For the WAGES OF SIN IS DEATH; but the gift of God is eternal life through Jesus Christ our Lord."
Romans 6:23
"But after thy hardness and IMPENITENT HEART treasurest up unto thyself wrath against the day of wrath and revelation of the righteous judgment of God"
Romans 2:5
4 - Christ was CONDEMNED on the cross and became the PAYMENT for OUR SINS.
"But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us."
Romans 5:8
5 - The GOODNESS of God found in the gospel should lead us to REPENTANCE & FAITH in Christ!
"...not knowing that the goodness of God leadeth thee to REPENTANCE?" Romans 2:4
"That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation."
Romans 10:9-10
"For whosoever shall call upon the name of the Lord shall be saved."
Romans 10:13