Romans 6:6-7

We know that our old self (our human nature without the Holy Spirit) was nailed to the cross with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin. For the person who has died (with Christ) has been freed from (the power) of sin.  

It doesn’t matter whether we are new or old Christians. What matters is eternal life and freedom from sin and spiritual death. We don’t have to follow the old nature or give in to tempting influences. Sin no longer has power over us unless we let it. Every day is a new day to work on becoming more like Christ.