The importance of Christ’s words: ‘You are already clean’, can be overlooked, or become lost, through seeing them as no more than a part of the symbolism of a teaching-image, which he based upon vines and vine-dressing. Instead, they are central to what Christ said: and their meaning is at the heart of many of his of teachings, about salvation, and how it is brought into being.
Some versions say: ‘already made clean’: confirming that spiritual cleansing comes about through actions other than our own; and that what we have to do; is to claim that truth, and, through faith, build our lives upon it.
At John 17: 17: Christ prayed to God: asking that his followers should be blessed in a special way:  ‘Sanctify them by the truth; your word is truth.’
To ‘Sanctify’ is to make holy: to set apart, to make sacred and saintly. Christ asked the Father to do the necessary sanctifying: he did not ask that his followers should be helped to sanctify themselves.
St. Paul had many positive things to say about the power of God’s word to remove all impediments, and to reveal life-giving and life-changing truth.
At Ephesians 5: 25+26, he uses an image very similar to ones that Jesus used. ‘Christ loved the church, and gave himself up for her, that he might sanctify her, having cleansed her by the washing of water with the word’.
Firstly, Paul highlights the motive for divine action: ‘Christ loved the church’.
Next, he tells of the manner of love’s expression: ‘He gave himself up for her’.
He goes on to show that Christ’s powerful reason for his actions; was that ‘He might sanctify her’, to make the Church holy, and fully acceptable to God.
Having touched on the motive, manner and reason for Christ’s actions; Paul points to the means by which such blessing was brought about.
He states that, just as water has the power to wash away dirt: so the application of divine truth; has the power to effect needful cleansing in the Church: thus making it an open, two-way channel of communication, between God and mankind.
Human nature often behaves in strange, even perverse, ways. A great truth: put in the form of a simple image; will make some people very disdainful.
Taking the view: ‘Surely, there is more to it than that’; they will either ignore the whole thing, or else begin to search for deeper implications, that are simply not there to be found.
Today, many people, who believe themselves to be Christians: risk losing sight of the truth; and even losing out altogether; as they, too, “search for deeper implications that are not there to be found”.
Christ often used simple images, to teach people about God’s requirements of them: and about how ‘achieving’ must not stand in the way of  ‘believing’.
He taught that belief, held on to, through faith; was the one great requirement that set people firmly upon the road to salvation: and urged his followers to walk that way. The Gospels and Epistles show that many accepted the Lord’s teaching  - and that many did not.
Today, through looking elsewhere: many people risk becoming part of those who do not fully accept God’s way of doing things.
They teeter on the edge of a spiritual adventure; of a new beginning that will never be theirs, as long as they fail to accept what Christ actually taught; and, instead, continue to wander down paths that God has not set before them.
‘There must be more to it than that’, sounds plausible: but can be a dangerous concept: in that its persuasiveness has the ability to lead people far astray. It can persuade genuine seekers to waste spiritual energy, in search of deeper implications that, as twice said; are simply not there to be found: and, in so doing, put their spiritual lives at risk.
The Old Testament required believers to fully obey the law. Only then, could they move towards the perfection that led to ongoing life with God. Such teaching can produce concepts of ‘up and doing’ action, leading on to eventual ‘achievement’.
The New Testament requirement is that we should fully accept what Jesus Christ has achieved on our behalf: and place all our hopes in him.
Only then will his perfection be counted to us; and only then will his life fully renew our lives, and keep us spiritually safe.
It is a matter of principle becoming practice; something like this. Through Christ: God thinks of mankind in terms of the principle of perfection. Such perfection needs to be anchored, before it can become fulfilled.
It is firmly anchored at the heart of God’s great scheme of things; and it is fulfilled, in the lives of individual people, at the moment when they accept Jesus Christ as their personal ‘God, Saviour and Lord’.
Their deliberate acceptance becomes a catalyst; that converts the hope of the divine principle, to the actuality of Christ’s perfection, at work within them.
Individual acceptance-events become like milestones in peoples’ lives; and are encouraging markers in the ongoing, corporate life of the Church.              
Although human frailty and sin exists within the Church; the divinely established principle of perfection cannot be adversely affected by it.
Christ’s cleansing of us, and making us entirely acceptable to God the Father, has little to do with any increase in our theological understanding; and very much to do with divine mercy, love and grace.
Divine mercy, love and grace, are always on offer: but their application does not ‘just happen’. Instead, they are brought into being; and made to happen.
This is effected, when contrite sinners actually acknowledge, and confess, the sins and shortcomings that need attention, (at that time) and, in consequence, are ‘cleansed from all unrighteousness,’ as 1. John 1:9, puts it. 
At that time’ is a good concept, and very realistic. It recognizes the almost certainty of eventual, further sin: and the resultant need of further mercy, love, grace and forgiveness
1. John 1:7, says that ‘the blood of Jesus Christ purifies us from all sin’.  
Three things are to be noted here. Firstly: not from ‘some sin(s)’ but ‘from all sin’.  Secondly, the blood of Christ not only cleanses us, but also purifies us, which is a big step farther, than cleansing alone.
Thirdly, and most importantly, it is neither the amount of our theological knowledge, nor the degree of our faith that cleanses us; but the historical act of Christ dying for our sins: to which truth, our faith makes claim.
At the ‘Last Supper’: Peter asked that, not only his feet; but also his hands and head, should be washed.  Jesus replied: ‘A person who has had a bath, needs only to wash his feet; his whole body is clean’ ‘John 13:10). 
Just as someone may have a bath; then walk along a dusty road, to visit a friend, and have need to wash the dirt off their feet: so with the man or woman who has fully accepted Jesus Christ, as ‘God, Saviour and Lord’.
He or she is certain to sin somewhat, and probably often, in their ‘journey of life’. Each time that happens, there is need to have those sins washed away, as well - again, by the action of the Spirit of Christ.
When we sin afresh: there is no need to even begin to consider, let alone attempt to undertake, a re-acceptance of Christ himself; for the original acceptance is still firmly in place; still perfect in principle – by God’s will.
It was to his disciples’ original acceptance of him, still firmly in place, that Christ referred, when he said, at John 15:3, ‘You are already clean’.
Even their eventual denial and abandonment of him; could not adversely affect the principle of what they had done; when they first said ‘Yes!’ first followed their Lord, and received the seal of divine approval.
And so it is with Christians: today. God does not expect perfection of us: but applies Christ’s perfection to us  -  as he does things his way.
It is upon our original acceptance of Jesus, as our personal Lord, that we stand before God, who, in the light of that event…
…looks upon us; sees the Spirit of Christ at work within our lives, and then says: ‘You are already clean’.   Amen