To those of you who say you now know God (or should I say, now that God knows you!), why would anyone want to go back to their sin again, and become slaves oncemore to the weak and useless spiritual principles of this world?

PLEASE! Think carefully about what is right, and stop any sinning you might be doing, for (to your shame) I’ll say that some of you don’t actually know God at all.
Everything is pure to those whose hearts are pure. But nothing is pure to those who are corrupt and unbelieving, because their minds and consciences are corrupted. That is why the world is like it is, and why even people who say they believe get wrapped up in the cares of this world again… and although it sounds harsh, such people who CLAIM they know God actually deny Him by the way they live… and because of that, they are detestable and disobedient, and worthless for doing anything good as God sees good.
It is written that if someone claims, “I know God,” but doesn’t obey God’s commandments, that person is in fact a liar and is not living in the truth. But on the flip side, those who obey God’s word truly show how completely they love Him by the way they live, and how they treat God, themselves and others around them. 
This is the key: this is how we know we are living in Him. Since we know that Christ is righteous, we also know that all who do what is right are God’s children. We should judge a tree by its fruit.
Dear friends, we who have fully turned to Christ are already God’s children, but He has not yet shown us what we will be like when Christ appears. We await the resurrection of the dead, and the casting away of these corrupted bodies in exchange for the incorruptible new ones! But even before that happens, we know that we will be like Him, for then we will see Him as He really is.

Let me reiterate that those who obey God’s commandments remain in fellowship with Him, and He with them. And we know He lives in us because we are aware that the Spirit He gave us lives in us; the kingdom of God is within us.
Those around us who know God will also listen to us, for we both belong to God. If someone does not belong to God, they do not listen to us. That is how we know if someone has the Spirit of truth or the spirit of deception. Again, we judge the tree by its fruit.
So, let us continue to do our very best to love one another, for all pure love comes from God. Anyone who loves like He loves is a child of God and knows God in the secret place. But anyone who does not love purely does not know God, for God is holy love. We believers know how much God loves us because of the cross, and we have put our trust in His love because we value the shed blood of the Christ. I’ll repeat that God is HOLY love, and thus all who live in that kind of love live in God, and God lives in them.
I have written this to you who believe in the name of the Son of God and who seek to obey Him, so that you may know you have the ‘deposit’ down for receiving eternal life.

We who know that we are children of God also know that the world around us is under the control of the evil one. So, we should do our utmost to follow only what is good, and shun wickedness entirely. 
Remember that those who DO good actually prove that they are God’s children by producing such fruit of the Spirit, and that those who do evil prove that they do not know God because they reject the cross and do the corrupt works of their father, the devil.
We should know without a shadow of a doubt that the Son of God has come, and that He has given us understanding so that we can know the true God through Him. And even now, we live in fellowship with the true God because we live in fellowship with His Son, Jesus Christ, through the indwelling and guidance of His Spirit in our lives.

YHWH is the only true God, and He is eternal life! Praise His name forever! So be it!