.
No, no, no, no, no! Would they be saved people if they were to walk in darkness? No. But the word if indicates that at the time of writing there was no evidence that they were doing anything of the sort.
6 If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth:
7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.
8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
10 If we say that we have not sinned, we make him a liar, and his word is not in us.
John is given a series of truths.
If we, that is any of "us", say we have fellowship with God, but in reality we, whomever we are, in reality, we are walking in darkness, and are liars, and don't actually do the truth.
This is a simple truth and simply expresses.
I can, we can, we say many things. But we are liars if we walk in darkness, while claiming to have fellowship with God. We don't have fellowship with God.
Contrarywise, IF we are walking in the light, then we actually do have fellowship one with another. And in this reality, the blood of Jesus is cleansing us from all sin.
These are simple declarative statements that explain that whatever we may declare about ourselves, there is a reality quite separate from our words. We are either actually in darkness, or actually in light.
I don't believe John is writing in hypotheticals here, as if he were saying,
(not a quote) If we say that we have fellowship with him, and 'were we then to' walk in darkness, we 'would be' lying, and 'would not be doing' the truth:
Instead he's laying out a foundation. We can say we have fellowship with God, but if we walk in darkness, that's just a lie. We're not doing truth.
We can say we haven't sinned. We can say we don't sin. That we have no sin. But a life of darkness puts the lie to these words.
But if we confess . . . But if we say the same thing as God says, if we confess our sins, Then, God is faithful, Just, to forgive our sins, and to cleanse us from all unrighteousness. And then, the words, I have fellowship with God, are true.
Much love!