In my scriptural opinion, no believer still has a sin 'nature'. We still have sin in the flesh, but we do not have a sin 'nature'. In the very core of our being we are united with Christ via the Holy Spirit, and that makes us
new creations:
"17Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come." (2 Corinthians 5:17 NASB italics in original, bold mine)
A pastor explained it like this. Before we were born again,
righteousness was the invading enemy force that we chaffed against, and sin was the thing we so longed to embrace. But now as born again, Spirit-sealed Christians
sin is the invading enemy force that we chaff against, and
righteousness is the thing we long to embrace. There has been a fundamental change of nature within us.
It is from the
flesh that the temptations to sin arise. They don't come from the new, transformed us. What remains until the day of redemption is the flesh body that has yet to be glorified, and it is from that flesh that we struggle with sin. I say
struggle with sin, not embrace it willingly like we did before we became new creations in Christ when our struggle was with righteousness.
Paul describes the change within us as a change of marriage partner (Romans 7:1-6 NASB). Before Christ, we were 'married' to sinful flesh, the law acting as a kind of legal marriage license that kept us bound in obedience to marriage partner 'flesh' (Romans 7:5 NASB). But when 'flesh' died on the cross with Jesus we were no longer legally bound by the law to have to stay in marital obedience to old husband 'flesh', because marriage ends when the husband dies--Romans 7:3 NASB. A death has occurred, so we are now free to be joined in marital obedience and submission to a new marriage partner, Jesus Christ, to whom we now bear fruit (Romans 7:4 NASB).
Paul calls our old life
before Christ as being 'in the flesh' (Romans 7:5 NASB, Romans 8:9 NASB). But he says we are no longer 'in the flesh'
if we have the Spirit of God in us. He didn't say we are are no longer in the flesh when we obey the Spirit. He says that just by virtue of having the Holy Spirit in us we are no longer 'in the flesh' (Romans 8:9 NASB). That's where I see the truth that we no longer have a sin nature, but rather the new nature of Christ. As Christians, we are no longer 'in the flesh'.