By your quotes you show how faith overcomes the world:
**2By this we know that we love the children of God, when we love God and observe His commandments. 3For this is the love of God, that we keep His commandments; and His commandments are not burdensome.**
John was addressing people that were already born again; converts of Jesus Christ, just like him:
“And hereby WE do know that WE know him, if WE keep his commandments. He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.” John 2:3,4
Another good confirmation of who he’s writing to:
“Let that therefore abide in you, which ye have heard from the beginning. If that which ye have heard from the beginning shall remain in you, ye shall continue in the Son, and in the Father. And this is the promise that he hath promised us, even eternal life. These things have I written unto you concerning them that seduce you. But the anointing which ye have received of him abideth in you, and ye need not that any man teach you: but as the same anointing teacheth you of all things, and is truth, and is no lie, and even as it hath taught you, ye shall abide in him.” John 2:24-27
There is no separation of faith in Christ, and faith in his commandments. If we believe in Jesus Christ, we believe his words; even believing in him through “their” (the apostles) word (John 17:20).
The Israelites shed the Passover blood, putting it on the doorways of their homes (a physical act that was a confession of faith), and were spared. But their final separation, from the curse of death by the Egyptians, didn’t happen until crossing the Red Sea. They believed and were baptized.
“And were all baptized unto Moses in the cloud and in the sea.” 1Cor. 10:2
But the questions still beg to be answered.
How do you know if you've lost your salvation?
How can you get it back?
No one can keep all of His commandments even if we just limit them to just the Ten.
If you break one commandment, does that cause you to lose your salvation?