It would be my pleasure. I love 1 John 1:7.
1 John 1:7 says,
"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." (1 John 1:7).
Some context:
5 "This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all.
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."
(1 John 1:7).
Okay, let's take the first part of the verse:
"But if we walk in the light, as he is in the light,..." (1 John 1:7).
The word "if" suggests a possibility or alternative to doing something else. For example: Rick could say to Bob, I will show up your house tomorrow IF I get all my work done around the house. So the word "if" suggests a possibility and not a guarantee. 1 John 1:7 does not start off talking about those who are regenerated will walk in the light as he is in the light. John is talking to believers and he says, "IF" we walk in the light. Compared to what? What is the alternative to not walking in the light?
The previous verse is the alternative to not walking in the light.
1 John 1:6 says,
"If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth" (1 John 1:6).
This sounds very similar to 1 John 2:4 that says,
"He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him." (1 John 2:4).
To know him (the Lord) sounds like having fellowship with him (the Lord). Both 1 John 1:6, and 1 John 2:4 talk about lying and the truth not being in that person by what they are doing (i.e. walking in darkness and not keeping his commandments). What is the truth that is not in them? Jesus. For Jesus says I am the way,
the truth, and the life (John 14:6). Jesus even said this before in John 15:10.
"If ye keep my commandments, ye shall abide in my love; even as I have kept my Father's commandments, and abide in his love." (John 15:10).
"But if
we walk in the light,..." (1 John 1:7).
The word "we" is referring to us believers.
In 1 John 1:1-4, John uses the word "we" in his opening letter, and he is definitely referring to himself and other believers or apostles he most likely knows.
He desires to have fellowship with the believers he is writing to. These are believers that John is writing to because he calls them as 'brethren" (1 John 2:7). He also tells them, "I write unto you, little children, because your sins are forgiven you for his name's sake. I write unto you, fathers, because ye have known him
that is from the beginning." (1 John 2:12-13). So these are definitely believers that John is writing to here.
"But if
we walk in the light,..." (1 John 1:7).
The word "
light" is referring to "
GOD." For 1 John 1:5 says, "
God is light, and in him is no darkness at all." The question we must ask from 1 John 1:5 is, "
What is the darkness that is not in GOD?
1 John 1:6 says, "we have fellowship with him, and walk in darkness, we lie, and do not the truth" But this does not help us to identify what darkness is yet. It merely tells us that we (professing believers) say we know Him, and we walk in darkness, we lie and do not the truth.
So what is this darkness?
1 John 2 gives us the answer or key.
So as we can see from the highlighted verses above in verse 9, and verse 11 in 1 John 2, we know that "
hating one's brother" is to be "
in darkness"; And verse 11 adds that "
hating one's brother" is "
walking in darkness."
So the darkness that is not in GOD = hating one's brother.
1 John 3:10 even confirms this.
"In this the children of God are manifest, and the children of the devil: whosoever doeth not righteousness is not of God, neither he that loveth not his brother."
(1 John 3:10).
So we know those who are truly of GOD vs. those who are of the children of the devil by the fact that the person who does not righteousness is not of GOD, and neither if they love not their brother. Meaning, they hate their brother.
So if one hates their brother, they are not of GOD.
1 John 3:15 nails this point home even more.
"Whosoever hateth his brother is a murderer: and ye know that no murderer hath eternal life abiding in him." (1 John 3:15).
It says whoever hates his brother is like a murderer, and no murderer has no eternal life abiding in them. So if one hates their brother, they have no eternal life or salvation.
So what is "
walk in the light" mean in 1 John 1:7?
Seeing that walking in the darkness is hating your brother, and loving your brother is abiding in the light according to 1 John 2:10-11, it is easy to conclude that "walk in the light" in 1 John 1:7 is "
to love your brother."
So far we have,
"But if we walk in the light,..." (1 John 1:7).
My commentary below is in blue brackets:
""But
if [suggesting a possibility and not a guarantee] we [believers] walk in the light [to "love our brother" is abiding in the light; The light being representative here of GOD],..." (1 John 1:7).
In other words, this part of 1 John 1:7 is essentially saying,
"if we believers love the brethren abiding in the light of GOD,..."
The next part of the verse says,
"
But if we walk in the light, ...as he is in the light, we have fellowship one with another,..." (1 John 1:7).
We know "the light" is GOD (because 1 John 1:5 says GOD is light).
GOD generally refers to GOD the Father, although it can refer to the other members of the Trinity or the Godhead.
1 John 1:3 says,
"That which we have seen and heard declare we unto you, that ye also may have
fellowship with us: and truly
our fellowship is with the Father, and with his Son Jesus Christ."
Jesus says, "Believe me that I
am in the Father, and the Father in me: or else believe me for the very works' sake." (John 14:11).
The "he" that is in the light is Jesus. The word "he" here refers to "Jesus," and the word "light" is referring to the "Father." In other words, 1 John 1:7 is saying up to this point,
"If we walk in the light of God
[by loving our brother], as Christ does within God the Father, we have fellowship with one another..."
In short, if we love our brother, we have fellowship with both God the Father (Who is the Light), and Jesus Christ.
Now, let's look at the next part of the verse.
"
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." (1 John 1:7).
Okay, this part of the verse is pretty straight forward in what it says and it does not need any decoding. We know that being cleansed of all sin by the blood of Jesus relates to salvation. But if you really need a verse, Romans 5:9 says,
"Much more then,
being now justified by his blood, we shall be saved from wrath through him." (Romans 5:9).
So in 1 John 1:7, being cleansed of all sin by the blood of Jesus Christ relates to salvation.
"In whom
we have redemption through his blood, the forgiveness of sins, according to the riches of his grace;" (Ephesians 1:7).
But 1 John 1:7 gives us the proper way to continue in the salvation of Christ or His blood after we are saved by the grace of Christ.
The first half of the verse says we have to love our brother and as a result (the second half says) we will have fellowship with Christ and the Father, and the blood of Jesus Christ cleanses us of all sin.
Not loving one's brother means we abide in darkness (1 John 2:9-11), and or it means we are not of God. Loving your brother is a part of God's commands in the New Testament (See: 1 John 3:23). For John's whole point is about loving your brother in his 1st epistle. John says if we do not love our brother, we are not of God (1 John 3:10). John says if we hate our brother, no eternal life abides in us (1 John 3:15). Loving your brother is not an automatic thing always. It takes work as we see in James 2. The brethren did not show love or favor to the poor brethren and as a result they broke the royal law of love (i.e. to love your neighbor). James never said that they were unregenerate or never saved. James is telling them that they are missing something besides just having a belief alone in Christ. James made a point on this is driven home even more in the fact that this kind of action by them meant that they needed to show faith that was evidence by works of faith. For a faith without works is dead. For even the demons believe and tremble. For James says in James 2:24 that we are justified by works and not by faith alone. Yes, we are saved by God's grace through faith without works in the Justification Process by receiving the gift of God's grace by exhibiting proper faith in Christ (i.e. accepting Jesus as one's Savior, believing in His death and resurrection on our behalf, and seeking His forgiveness by way of prayer to Him), but our faith is not a mere mental acknowledgment of a certain set of facts about the Lord. Faith has to hit the heart, and it leads to right actions. It breaks a person whereby they are forever changed and they are a new creation in the way they think, and live. But some think that faith is easy believism or an acknowledgment to a certain set of facts. Some think this way and they borrow a little from the Sanctification category to make their belief alone-ism not look so morally bad. But they will never say Sanctification is for salvation (Even though the Scriptures teach that very thing like with 1 John 1:7).
That would be unloving and I wouldn't be walking in Light. It's a declarative warning, that's all. You are making a mountain out of a mole hill and inserting works to maintain salvation in place of grace. 
