I agree with you, but this can be the hardest thing for a Christian. To say "so it's just a matter of" almost makes it sound simple. Even the Apostle Paul lamented about doing what he did not want to do, and not doing what he wanted to do. Battling the flesh can be a lifelong struggle for Christians, and especially hard for newer Christians when Satan steps up the temptation to lure you away. There have been many who have given up on God because they couldn't win that battle with their flesh. We have to prepare newer Christians for this battle, and teach them not to get discouraged over it. There is a perception among some that when you become a Christian you no longer sin, and that is far from the truth. You no longer live a life of sin, and has been pointed out here, there is a difference.
How then was Jesus crucified?
By the will of God.
By the Word of God ,
By the power of God.
and albeit wicked men by their own will did it .
They did so in fullfilment of the scriptures.
"sin must come,but woe to them by whom it comes"
How then are we crucified? ".....with Christ"
By the will of God ,the Word of God and the power of God . It is an act of faith believing in the work of Christ.
Who was crucified for our sins .
"They who are Christs have crucified the flesh with the lusts thereof "
The struggle of Paul is often quoted to our 'comfort' (?) but never the last part of it "But thanks be unto God who GIVES us the victory through our Lord Jesus Christ"
The struggle I believe is that we still want to 'live' when God would have us die in Christ be buried with Christ and rise again a new creation in Christ .
But I like the thrust of the OP . Though I would argue against the general practice of denigrating the English translations .
For John says we shall not sin....................which is the main emphasis of the passage as the OP rightly pointed out .
"But IF we sin............" is not a get out clause and an excuse for sin. and where many emphasise IF we sin.
But its an IF , THEN we have an advocate with the Father........
"If we walk in the light as he is in the light then we have fellowship one with the other and the blood of Jesus Christ cleanses us from all sin"
As the blood of the natural body continually circulates around the body purifying and cleansing it from all that would do it harm.
So then as we abide in Christ and walk in the light and have fellowship one with the other then also the blood of Jesus Christ continually cleanse the body from all sin.
The body of Christ is a living organism as it were and our life in Christ and part of that body not only has a function but also ministers to each and each other as the Lord sees fit .
In Hebrews Paul speaks about under the old covenant the blood of bulls and goats could not put away sin and that therefore there was always a rememberance or concience of sin . But the blood of Jesus cleans the concience before God.
Indeed as the blood of Abel spoke to God of justice recompence and the sin of Caine .
So then is it not written that we come to the blood that speaks of better things than the blood of Abel?
For in a courtroom there are witnesses who speak on your behalf . So then does the blood of Jesus speak on our behalf of sin already judged . Of mercy and forgiveness and an acceptable sacrifice .It speaks of adoption, acceptance, righteousness and the justice and glory of God .
Do we not stand before God ?
and when does that precious blood not speak?
Does not the Lord for ever make intercession for us?
Is he not a "high priest for ever........" (Hebrews)
Not in the tabernacle made with hands but in that which was made by God.
Then I say even as the tabernacle made with hands was 'clothed ' with the white linen of righteousness round about .
Then so are we clothed with the righteousness of Christ .
and even as the silver foundation of the holy place and the holy of Holy spoke of the redemption and the purchased possession , so then are we a purchased possession .Twice Gods . First by creation and second by redemption and new birth.
The devil would parade our sins before us and hope to hinder our worship of God and to come boldly into the presence of God .
But we are COUNTED righteous before God because of Jesus . Or HIS righteousness is imputed to us.
It is then that righteousness is imparted to us by the Holy Spirit and then we in practice do works of righteousness by and through Him who enables us .
It should not then be IF we sin. But more 'if' we sin.
like the folly of a wise man is like a fly in the ointment .
"Ye fathers ye know Him who is from the beginning "
That is to say then the Creator of all things .
I would argue that if we do know Him in any measure "who is from the beginning ."
Not only will we understand we did not create ourselves but that also we are a new creation in Christ Jesus and "old things have passed away and behold all things have become new"
I would further state that the church had better repent of its unbelief of the book of genesis and stop compromising with the world about it .
For how can we know Him who is from the beginning if we do not believe the book of beginnings?
and if we do not believe God who spoke in the beginning .Will we n ot also believe the modern day serpent ? and learn nothing from what was at the beginning?
Surely repentance must or does include the reversal of the same error that man committed in the beginning ?
In truth a tree will stand as long as its roots are deep enough no matter what storms may come .
Are we not or should be rooted and grounded in God ?
are we not as trees planted by the rivers of living water?
Do not then those same waters flow up in and through us ?
If you cut the top of a tree off .Water will literally bubble up like a mini fountain.
Then if our roots our rooted in Him who is "from the beginning" nothing in this world will move us or beguile us .
"little children your sins are forgiven and ye know the father ......." 1John.
Little children can be deceived .
There is coming a day when "if it was possible even the very elect would be deceived......."
Such subtlety and deceit that it will be only by the Holy Spirit we will be able to discern the difference between the true and the false .
In truth it is always by Him who leadeth us into all truth that we do so any way .
But it is" by practice we are able to discern good from evil" an interesting statement of Paul when you consider that God gave Adam and Eve HIS knowledge of good and evil in the garden of eden. It was their decision to choose what was good in thier own eyes that led to the disaster that followed. Then as now.
Thus in Christ and by Him our senses are changed to see things as they truly are in GOD's eyes and to act accordingly .
The temptations of the Lord in the wilderness were all to see things from the world the flesh and the devils eyes and to act accordingly .
But Jesus full of the Holy Ghost and the Word of God put things in thier right perspective and order and "overcame the wicked one"