*** Then the believer is "free" to commit sins.***
It is an unfortunate possibility. See Gal 5:13 for the admonition not to misuse freedom.
We are exhorted by almost all apostolic writers to, "...lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us," (Heb 12)
or...
"Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry. On account of these the wrath of God is coming. In these you too once walked, when you were living in them.
But now you must put them all away: anger, wrath, malice, slander, and obscene talk from your mouth. Do not lie to one another, seeing that you have put off the old self with its practices and have put on the new self, which is being renewed in knowledge after the image of its creator."
Both passages point to the reality of sin in the life of the believer. But both of them deal with sin as a nusaince and direct believers to keep their eyes on the prize of heaven which await them.
***PM, what are the consequences of sin?***
To a large degree it depends on where you stand with regards to the new covenant ratified by the blood of Christ.
"This is the covenant that I will make with them
after those days, declares the Lord:
I will put my laws on their hearts,
and write them on their minds,"
then he adds,
"I will remember their sins and their lawless deeds no more."
Where there is forgiveness of these, there is no longer any offering for sin.
If you are under the new covenant then sin can rob you of your blessing, it will prevent you from fellowshipping and walking with God throughout your day, it will prevent you from being used by Him to reach or bless others, it will prevent your prayers from being heard, it will bring great sorrow into your life and it may even result in your life on earth being cut short - but it will not send you to hell.
It's a bit like double jeopardy. Once the punishment for sin has been paid, it can not be required to be paid again. Once Christ has died in our place and we have accepted his death for us by faith, and by that faith God has accounted us righteous - it would be unjust of God to require that the sins be paid for again. And remember, when Christ died ALL your sins were yet in the future.
"If God is for us, who can ever be against us? Since God did not spare even his own Son but gave him up for us all, won't God, who gave us Christ, also give us everything else?
Who dares accuse us whom God has chosen for his own? Will God? No! He is the one who has given us right standing with himself. Who then will condemn us? Will Christ Jesus? No, for he is the one who died for us and was raised to life for us and is sitting at the place of highest honor next to God, pleading for us." - Rom 8