Thus it is possible that a serial murderer or a pornographer can still be an active participant in murder or pornography and be "saved" according to this mode of thinking.
The problem here is simply a false view of what salvation is, where it is perceived as purely forensic and as such is separate from an actual transformation of the heart. Under the above stated view the transformation of heart occurs sometime
after salvation instead of at the same time as salvation.
Jesus came to set people free from their sin as opposed to setting people free in their sin.
A serial murderer and a pornographer are enslaved to sin and therefore are the servants of sin. These people obey sin instead of obeying righteousness. If these people are set free from this bondage through Jesus Christ via grace (the quickening power of God) through faith (abiding willingly in that power) then this service of sin has ceased. There is nothing forensic in this situation whereby one can then fall into the error of the bolded statement in the quote above.
Paul wrote on this very clearly...
Eph 2:1 And you hath he quickened, who were dead in trespasses and sins; "
Quickened" literally means "made alive."
Eph 2:2 Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience:
Eph 2:3 Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.
"Conversation" means "conduct" and Paul is referring to how those whom are saved "once walked." It is the lost who walk in the lusts of the flesh, fulfilling the desires of the flesh and mind, and whom are therefore "children of wrath." Their spiritual state begets the wrath of God because they are in rebellion to God in that they choose to serve evil.
Eph 2:4 But God, who is rich in mercy, for his great love wherewith he loved us,
Eph 2:5 Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved
The quickening brings one from a dead state (being unreconciled, condemned and dead to God) to a living state (reconciled, uncondemned and alive to God). Paul annotates this quickening as being by the grace of God.
Eph 2:6 And hath raised us up together, and made us sit together in heavenly places in Christ Jesus:
The quickening involves a raising up, a resurrection so to speak.
Paul speaks of this raising up elsewhere...
Rom 6:1 What shall we say then? Shall we continue in sin, that grace may abound?
Rom 6:2 God forbid. How shall we, that are dead to sin, live any longer therein?
Rom 6:3 Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death?
Rom 6:4 Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.
Rom 6:5 For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection:
Rom 6:6 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin.
Rom 6:7 For he that is dead is freed from sin.
The bondage of sin is broken through dying with Christ and a new bondage to righteousness takes its place when we are raised up with Christ. Hence the "old conduct" is in "times past."
Col 2:10 And ye are complete in him, which is the head of all principality and power:
Col 2:11 In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
Col 2:12 Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
Col 2:13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
Again Paul writes on how the Christian puts off the body of the sins of the flesh by the circumcision of Christ, a circumcision of the heart, a transformation of the inward man. This transformation of the inward man necessitates the outer transformation. We are "saved by grace" THROUGH "faith" and not of ourselves and not of works (ie. anything we could do apart from the quickening power of God).
Eph 2:8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
Eph 2:9 Not of works, lest any man should boast.
Eph 2:10 For we are his workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them.
The "Lordship Salvation" debate is erroneous because those for and against are promoting a forensic view of salvation which completely separates a transformed heart from being set free from sin.
There is no salvation without heart transformation. There is no salvation in the continued service of sin. It is Satan who wants to deceive people into believing in a forensic salvation in order they they believe they can "sin and not surely die" (ie. rebel against God and not surely die).
No genuinely saved individual is in rebellion to God. The rebellion has ceased. They may not know much but their heart is clean and in this state growing in the grace and knowledge of Jesus Christ is possible. A sheep may be immature but a sheep may not be a rebel to God.
God bless.