I would have to agree with Truster - this statement is works salvation-oriented.
First off, you just ignored the many scriptures provided in support of my statements. Categorically dismissing the evidence because you don't like the conclusion isn't conductive to the search for truth.
Secondly, The scriptures teach that we are judged by our deeds - and eternal life is the reward for our good deeds (see Romans 2:6-11; James 2:18-20; and the parable of the sheep & goats in Matthew 25 for a start)
We are of God: he that knoweth God heareth us; he that is not of God heareth not us. Hereby know we the spirit of truth, and the spirit of error.
Beloved, let us love one another: for love is of God; and every one that loveth is born of God, and knoweth God.
He that loveth not knoweth not God; for God is love.
In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him.
Herein is love, not that we loved God, but that he loved us, and sent his Son to be the propitiation for our sins.
Beloved, if God so loved us, we ought also to love one another.
No man hath seen God at any time. If we love one another, God dwelleth in us, and his love is perfected in us.
I John 4:6-12
John paints the picture of those that know God and those that don't. Those that know Him love the brethren - but at the heart of it is God's love predicating our love. And it is intertwined with those that hear John and his teaching (and agree with what the church held). It is a matter of identification, not prescription - he isn't saying that knowing God comes with our efforts to love Him. Rather...
Great passage, but, to clarify, when he says "if we love one another" he is speaking of everyone, universally.
Luke 10:30-37 Jesus replied and said, “A man was going down from Jerusalem to Jericho, and fell among robbers, and they stripped him and [n]beat him, and went away leaving him half dead. 31 And by chance a priest was going down on that road, and when he saw him, he passed by on the other side. 32 Likewise a Levite also, when he came to the place and saw him, passed by on the other side. 33 But a Samaritan, who was on a journey, came upon him; and when he saw him, he felt compassion, 34 and came to him and bandaged up his wounds, pouring oil and wine on them; and he put him on his own beast, and brought him to an inn and took care of him. 35 On the next day he took out two [o]denarii and gave them to the innkeeper and said, ‘Take care of him; and whatever more you spend, when I return I will repay you.’ 36 Which of these three do you think proved to be a neighbor to the man who fell into the robbers’ hands?” 37 And he said, “The one who showed mercy toward him.” Then Jesus said to him, “Go and do [p]the same.”
Furthermore, and I can't stress this enough, love is not identification. Love is action. Christ serves as THE example of what love looks like: self-sacrifice for the sake of others. Christ didn't go to the righteous, he didn't go to those who were like him. He went to the poor, the forsaken, and the sinner.
John 15:13 Greater love has no one than this, that one lay down his life for his friends.
James 2:14-17 What use is it, my brethren, if someone says he has faith but he has no works? Can [n]that faith save him? 15 If a brother or sister is without clothing and in need of daily food, 16 and one of you says to them, “Go in peace, [o]be warmed and be filled,” and yet you do not give them what is necessary for their body, what use is that? 17 Even so faith, if it has no works, is [p]dead, being by itself.
We love him, because he first loved us.
I John 4:19
Or should we say that if we want God to dwell in us we must FIRST love Him? If we can't say that, then we have to admit that the love is a marker - an indicator - of God's love in us and our being born of Him.
John clarifies at the beginning of the next chapter what it means to love God:
1 John 5:3 For this is the love of God, that we keep His commandments; and His commandments are not burdensome.
To love God is to obey God, to fulfill his commandments, to do what is right. This, in turn, means loving others. God loves us first - but we must reciprocate that love first before he dwells in us.
So unless our love of God is an indicator - a fruit or a marker (so to speak) of our relationship with God - rather than that which we do to cause us to know Him - we must preach works salvation.
Our love isn't a mere indicator - it is something we ourselves must actively strive to do. Loving God means loving one another, and loving one another means caring about others and sacrificing of yourself to help them. Good works is our purpose, and we must devote ourselves to doing what is right. Hence we are constantly told to persevere, lest we be found wanting.
James 1:12 Blessed is a man who perseveres under trial; for once he has been approved, he will receive the crown of life which the Lord has promised to those who love Him.
1 Cor 9:26-27 Therefore I run in such a way, as not without aim; I box in such a way, as not beating the air; 27 but I [l]discipline my body and make it my slave, so that, after I have preached to others, I myself will not be disqualified.
Matthew 24:12-13 Because of the increase of wickedness, the love of most will grow cold, 13 but the one who stands firm to the end will be saved.
Hebrews 10:36 You need to persevere so that when you have done the will of God, you will receive what he has promised.
1 John 2:25 And this is what he promised us—eternal life.
THAT SAID...I believe this knowing Him is a progressive thing. But it all comes from Him and as we continue in Him, we grow in His love.
And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent.
John 17:3
As demonstrated in the OP, knowing God - and being known by God - are a matter of love. When we love one another, that is love for God. When we give to those in need, we are giving to God. And this is true regardless of one's belief. To love God isn't for God to love himself. It is for us to love God, for us to love others.
Paul, I believe, is saying that his life is being more and more conformed to Christ and he knows more of Christ and less of himself. More of Christ's love and less of his own. That seed was planted at conversion (I John 3:9) but it certainly has to grow. And all that attends that growth must be realized in his life as he presses on and does not look back - but perseveres to the end. That is lifelong - and goes well beyond simple acts of charity we may do to and for the brethren. It is ongoing change in us until we come into the maturity of the "perfect man" spoken of in Ephesians 4:13. That doesn't just include, but is centered in speaking the truth (doctrine) in love (the love of God being perfected in us). Growing up into Christ - the head - in all things.
Doctrine isn't necessary in the least for love. Doctrine is a guide that only has value when acted upon. If people do what is right without doctrine - then they demonstrate that they have the capacity for good independent of doctrine.
Romans 2:14-15 (Indeed, when Gentiles, who do not have the law, do by nature things required by the law, they are a law for themselves, even though they do not have the law. 15 They show that the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts sometimes accusing them and at other times even defending them.)
Love isn't doctrine or faith. It is not found in some mystery nor does it require great knowledge. Love is a matter of heart: what you value, how you choose to live your life, how you choose to treat others.
1 Cor 13 If I speak in the tongues[a] of men or of angels, but do not have love, I am only a resounding gong or a clanging cymbal. 2 If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but do not have love, I am nothing. 3 If I give all I possess to the poor and give over my body to hardship that I may boast, but do not have love, I gain nothing. 4 Love is patient, love is kind. It does not envy, it does not boast, it is not proud. 5 It does not dishonor others, it is not self-seeking, it is not easily angered, it keeps no record of wrongs. 6 Love does not delight in evil but rejoices with the truth. 7 It always protects, always trusts, always hopes, always perseveres.8 Love never fails. But where there are prophecies, they will cease; where there are tongues, they will be stilled; where there is knowledge, it will pass away. 9 For we know in part and we prophesy in part, 10 but when completeness comes, what is in part disappears. 11 When I was a child, I talked like a child, I thought like a child, I reasoned like a child. When I became a man, I put the ways of childhood behind me. 12 For now we see only a reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known. 13 And now these three remain: faith, hope and love. But the greatest of these is love.
Look at how Paul describes love. He differentiates it from the various gifts: faith, speaking in tongues, prophecy, knowledge, etc. Love isn't any of these things - love is a matter of who we are, our disposition, how we treat others. Love is patient, kind, does not envy, isn't easily angered, etc.
(6) And hath raised us up together, and made us sit together in heavenly places in Christ Jesus: (7) That in the ages to come he might shew the exceeding riches of his grace in his kindness toward us through Christ Jesus. (8) 
