I John

Whoever denies Jesus, the son, also denies God, His father.

I John 2:22-23
"Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son. Whosoever denieth the Son, the same hath not the Father: [but] he that acknowledgeth the Son hath the Father also"

Jesus gave His own life because of His love for us, and we should be prepared to do likewise if needs be.

I John 3:13-16
"Marvel not, my brethren, if the world hate you. We know that we have passed from death unto life, because we love the brethren. He that loveth not his brother abideth in death. Whosoever hateth his brother is a murderer: and ye know that no murderer hath eternal life abiding in him. Hereby perceive we the love of God, because he laid down his life for us: and we ought to lay down our lives for the brethren"

Any prophet who does not say that Jesus was God's son, incarnated in a human body, is speaking from the spirit of the antichrist.

I John 4:1-3
"Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world. Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God: and every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world"

Many have said that they are Christians, but have not lived as Jesus told them to.

I John 2:3-6
"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. But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him. He that saith he abideth in him ought himself also so to walk, even as he walked"

Because most people do not know God, they don't believe in Christ.

I John 3:1-2
"Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not. Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is"

God is love, and so we need not be afraid if we live in love with Him.

I John 4:16-18
"And we have known and believed the love that God hath to us. God is love; and he that dwelleth in love dwelleth in God, and God in him. Herein is our love made perfect, that we may have boldness in the day of judgment: because as he is, so are we in this world. There is no fear in love; but perfect love casteth out fear: because fear hath torment. He that feareth is not made perfect in love"

I John 5:16-17
"If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it. All unrighteousness is sin: and there is a sin not unto death."

We are unsure what "the sin that ends in death" is exactly. It may be blasphemy, which ends in spiritual death, as we see in Mark 3:29

"but he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation"

By obeying God, we can overcome the sinful pleasures of this world.

I John 5:4-5
"For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith. Who is he that overcometh the world, but he that believeth that Jesus is the Son of God? "

If we live in God's spiritual light, and shun the darkness of sin, then Jesus' blood will cleanse us of our sins.

I John 1:5-7
"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. If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth: 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"

Christ came to us with the message of eternal life, to which John can attest, having touched Him with his own hands.

I John 1:1-3
"That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, of the Word of life; (for the life was manifested, and we have seen it, and bear witness, and shew unto you that eternal life, which was with the Father, and was manifested unto us;) 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"