Ah, True Christians. What Biblical basis is there for saying that only real Christians are completely and utterly without sin? Ephesians 2:3 and Galatians 2:21 should provide food for thought.
I have had a look at the verses you quoted to get a better understanding of your theory.
Eph 2:3 All of us also lived among them at one time, gratifying the cravings of our sinful nature and following its desires and thoughts. Like the rest, we were by nature objects of wrath.
Gal 2:21 I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!"
The best way to state my belief is that a true Christian will not seek to willfully sin. No Christian should be thinking on any given day how do I sin today and get a way with it. A Christian may sin due to stress, strain, or ignorance, and grace applies. Infact grace applies to anyway a person may sin, no sin is not covered by grace. Grace exists, i.e. a Christian can sin, however note:
Rom 6:15 What then? Shall we sin because we are not under law but under grace?
By no means!
Rom 6:12 Therefore
do not let sin reign in your mortal body so that you obey its evil desires. Rom 6:13
Do not offer the parts of your body to sin, as instruments of wickedness, but rather offer yourselves to God, as those who have been brought from death to life; and offer the parts of your body to him as instruments of righteousness.
Continual sinning on purpose results in spiritual death, and eventually hell, as this topic is about hell I might as well put it in.
Rom 6:23 For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord.
It really worries me when I hear Christians joking about "If only you knew what God lets me get away with", "what God has forgiven me for" (in the present tense). Sure God will forgive but when sin becomes a life style it is shaky ground. I am not saying these people can not be saved but they do need to repent (turn around) Jas 5:19 My brothers, if one of you should wander from the truth and someone should bring him back,
Jas 5:20 remember this: Whoever turns a sinner from the error of his way will save him from death and cover over a multitude of sins.