Whilst it is true that we have an advocate IF we sin (1Joh 2:1) the context of that sin is NOT WILLFUL because if we willfully sin AFTER being cleansed (Heb 10:29, Hen 10:26-29) there is no more sacrifice. Jesus did not die as a cloak for ongoing rebellion. The blood of Christ is not a license to keep on sinning which is what Penal Substitution clearly teaches. The blood of Christ can be applied to sins of ignorance but CANNOT be applied to ongoing willful transgression.
How do I perceive the death of Christ (Atonement)? Jesus Christ died as both a sin offering (that our past rebellion be washed away) and as an example (so that we die with Him). Both aspects are essential in order that genuine reconciliation (return to favour) with God takes place.
What is propitiation?
Rom 3:25 Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
Propitiation - G2435 -hilastērion
Neuter of a derivative of G2433; an expiatory (place or thing), that is, (concretely) an atoning victim, or (specifically) the lid of the Ark (in the Temple): - mercyseat, propitiation.
Propitiation means Mercy Seat and it is where the past transgressions are washed away and we are made clean.
Isa 1:16 Wash you, make you clean; put away the evil of your doings from before mine eyes; cease to do evil; [The cessation of evil is a MANDATORY CONDITION, ie. Repentance is MANDATORY]
Isa 1:17 Learn to do well; seek judgment, relieve the oppressed, judge the fatherless, plead for the widow.
Isa 1:18 Come now, and let us reason together, saith the LORD: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool.
Heb 10:22 Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.
The blood was sprinkled in order to cleanse the offering. We are that offering...
Rom 12:1 I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.
Rom 12:2 And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
Look at this passage...
Heb 9:5 And over it the cherubims of glory shadowing the mercyseat (g2435); of which we cannot now speak particularly.
Heb 9:6 Now when these things were thus ordained, the priests went always into the first tabernacle, accomplishing the service of God.
Heb 9:7 But into the second went the high priest alone once every year, not without blood, which he offered for himself, and for the errors of the people: [sins of ignorance]
Heb 9:8 The Holy Ghost this signifying, that the way into the holiest of all was not yet made manifest, while as the first tabernacle was yet standing:
Heb 9:9 Which was a figure for the time then present, in which were offered both gifts and sacrifices, that could not make him that did the service perfect, as pertaining to the conscience;
Heb 9:10 Which stood only in meats and drinks, and divers washings, and carnal ordinances, imposed on them until the time of reformation. [The law could not purify the heart]
Heb 9:11 But Christ being come an high priest of good things to come, by a greater and more perfect tabernacle, not made with hands, that is to say, not of this building;
Heb 9:12 Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us.
Heb 9:13 For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:
Heb 9:14 How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God? [The blood purges the conscience of all defilement]
Satan wants people to reject the above scriptures in order to uphold a teaching where the blood of Christ cleanses ongoing rebellion whereby one can "SIN AND NOT SURELY DIE." Satan's very first lie is upheld as truth by so many who profess faith in Christ, by so many who still "work iniquity."
Can you sin and not surely die?
Do you really believe that you can go and murder someone and remain in a justified state before God? Do you really believe that one can be actively engaged in known transgression and be in a justified state at the very same time?