Not sure how this pastor you mention would get to sinless perfection from what Paul wrote in this verse... If anything, the verse seems to suggest an ongoing process, not an achieved end.
Well, what about this verse then?:
2 Corinthians 5:17
17 Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new.
Wouldn't becoming a "new creation" entail receiving a new heart? Wouldn't the deceitful heart of the "old man" be part of what has "passed away"? If not, why not?
This verse indicates a struggle against the habits and mindset of the "old man," the carnal, fleshly person we were before we were saved. Paul seems to indicate in his letter to the Romans that the struggle against the impulses of the flesh is a struggle to live out our new nature in Christ in the face of the inertia of flesh-centered living which has characterized our life but to which we are now made dead (Romans 6:1-18). You shoot a charging bear in the heart and the momentum of his charge may still move him toward you even though he's dead. A sinful life has "momentum" that must be overcome, too, habits of thought and behaviour that must be reversed or abandoned. As a man "reckons" himself "dead to sin and alive unto God," he overcomes the inertia of his past, sinful life and will begin to live a life of holiness where sin becomes the rare exception rather than the rule. Too many modern believers, though, think that the Christian life is a tight circle of sin>confession>sin>confession, 'round and 'round until death. The possibility of a life lived largely free of sin, they have decided, is an impossibility. This isn't the attitude of Scripture, however.
Romans 6:1-2
1 What shall we say then? Shall we continue in sin that grace may abound?
2 Certainly not! How shall we who died to sin live any longer in it?
Romans 6:11-14
11 Likewise you also, reckon yourselves to be dead indeed to sin, but alive to God in Christ Jesus our Lord.
12 Therefore do not let sin reign in your mortal body, that you should obey it in its lusts.
13 And do not present your members as instruments of unrighteousness to sin, but present yourselves to God as being alive from the dead, and your members as instruments of righteousness to God.
14 For sin shall not have dominion over you, for you are not under law but under grace.