True Christians are disciples of Jesus, the Word of God.

Yes. Sadly, many claiming to be saved will be rejected by Jesus because He never knew them.

• Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? And then will I profess unto them, I never knew you: depart from me, ye that work iniquity. Matthew 7:22-23.
• But he shall say, I tell you, I know you not whence ye are; depart from me, all ye workers of iniquity. Luke 13:27.

How can this be if they did many works in the "name of Jesus"? 

Answer: The name of Jesus is powerful in itself, and man's assessment of his own works is not binding on God. 

• Wherefore God also hath highly exalted him, and given him a name which is above every name: That at the name of Jesus every knee should bow, of things in heaven, and things in earth, and things under the earth; And that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father. Philippians 2:9-11.

As to authenticity, Jesus knows what the Word is and is not because it lives in Him. He knows who wants it and who doesn't. 

• Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, let every one that nameth the name of Christ depart from iniquity. 2 Timothy 2:19.

God's Word controls, and God's will (His works) are the measuring stick. 

• If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself. John 7:17.

Jesus will never reject those who seek the truth of the Word and do it.

• But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ [the Word of God], he is none of his. Romans 8:9 [Bracketed language added for clarity].

Jesus the Word must know you to be saved, meaning the Spirit of Christ, the Word of God, must dwell in the saved person. Thus, for us to live forever in Him, we want the same Word He has because He is the Son of God because of the Spirit, and more specifically, the Word of God, yet man has the gall to change the Word to suit himself.  

Yes. God IS the Holy Spirit. The Holy Spirit IS the Father, the Father's Word, and the Holy Ghost; and God is love. His Word IS our first love!

• We love him, because he first loved us. 1 John 4:19.

The King James Bible is the ONLY one that can be reconciled using only its own words. ALL other "versions" depart from (i.e., changed) the pure Word and cannot be reconciled using only the words in them; and this is a departure from our first love.

• I know thy works, and thy labour, and thy patience, and how thou canst not bear them which are evil: and thou hast tried them which say they are apostles, and are not, and hast found them liars: And hast borne, and hast patience, and for my name's sake hast laboured, and hast not fainted. Nevertheless I have somewhat against thee, because thou hast left thy first love. Remember therefore from whence thou art fallen, and repent, and do the first works; or else I will come unto thee quickly, and will remove thy candlestick out of his place, except thou repent. Revelation 2:2-5.

The church that left the pure Word has left its first love for another version that pleases it more, and it must repent and return to it.

God will not be mocked by people who change His Word to suit themselves.

• Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap. Galatians 6:7.

There is no excuse for blindly following the waywardness of another.

• And he spake a parable unto them, Can the blind lead the blind? shall they not both fall into the ditch? Luke 6:39.
• Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch. Matthew 15:14.
• Woe unto you, scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte, and when he is made, ye make him twofold more the child of hell than yourselves. Matthew 23:15.

Yes, count on it and be of good cheer. 

• Yea, and all that will live godly in Christ Jesus shall suffer persecution. 2 Timothy 3:12.

Many will be offended by the Word because of the persecution it will bring from the world.

• ...for when tribulation or persecution ariseth because of the word, by and by he is offended. Matthew 13:21.
• ...afterward, when affliction or persecution ariseth for the word's sake, immediately they are offended. Mark 4:17.

Jesus and the Word have overcome the world, so be of good cheer.

• These things I have spoken unto you, that in me ye might have peace. In the world ye shall have tribulation: but be of good cheer; I have overcome the world. John 16:33.

(Note: The peace Jesus speaks of is not for the world. It is for us, His followers- the disciples.)

• And Jesus answered and said, Verily I say unto you, There is no man that hath left house, or brethren, or sisters, or father, or mother, or wife, or children, or lands, for my sake, and the gospel's, But he shall receive an hundredfold now in this time, houses, and brethren, and sisters, and mothers, and children, and lands, with persecutions; and in the world to come eternal life. Mark 10:29-30.

Know it isn't them; it is the enemy working in them. 

• Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord. Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head. Be not overcome of evil, but overcome evil with good. Romans 12:19-21.

Many were of the enemy before becoming born again.

• Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind, Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God. And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our  God. 1 Corinthians 6:9-11.

When we became born again of the Spirit, we came out from among the lost who will die in their sins.

• Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you. And will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty. 2 Corinthians 6:17-18.

We must warn them to repent and be saved.