What is their rationale?   
   → doctrinal error
   → wrong baptism
   → church affiliation
   → appearance
   → language
   → associations
   → Jewish feasts
   → Greek and Hebrew

Elitist Christians are the equivalent of the Pharisees of Jesus day.   Such do not distinguish between the gift of God, Eternal Life, and Soul Salvation.   
Furthermore, they fail to understand that the seed is the Word Of God, the Holy Spirit is the life producer and their only contribution is the Good Ground of Faith.   

For it is the Lord which worketh in you both to will and to do of his good pleasure. Phi 2:13 Your will is a part of your soul.     It is that part of you which opens and closes doors.      When you open your heart to the Lord Jesus Christ, you enable Him to recreate you in the New Birth.      As you submit your will to His Holy Spirit you enable His will to manifest in you.      To the extent that you work out your Soul Salvation through the submission of your will to His, you will see the Holy Spirit perform holy acts through your life.      It is the New Spirit being that you are, which you allow to manifest, which is in sync with the Holy Spirit, which directs your will and actions.

The main reason Elitist Christians exist is the subtlety of Satan who plays on the pride of life.   

For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world. 1Jn 2:16 We are Spiritual Minded and no longer Carnal Minded.

The reality of the laws of the Kingdom of Jesus Christ is that Abundant Life is the blessing of obedience while the `curse` of disobedience is the lack of Abundant Life.   

At the Judgment Seat Of Christ the obedient will receive rewards while the disobedient will be saved as by fire receiving no rewards.   

For by grace are ye saved through faith; and that not of yourselves: it is the gift of the Holy Spirit: Eph 2:8 We are saved because the Holy Spirit willed it Heb 8:12 and made it possible and legal through the shed blood of Jesus Christ Heb 10:10.      Salvation is totally an act of His unmerited favor - Grace.     Our part is to have faith in His Word - the Written Word and the Incarnate Word Act 16:31.      We have all been given The Measure Of Faith Rom 12:3.      It is that gift of faith than enables us to believe on the Lord Jesus Christ through whom we receive Grace 2Pe 1:3.      Once we believe on the Lord Jesus Christ, the Faith Of Christ which is a fruit of His Holy Spirit provides all the benefits of Grace Rom 5:2.      The Faith Of Christ is the foundation of Grace Rom 5:19.      We are not supposed to trust in our faith but, rather, trust in the Faith Of Christ - the faith that is the fruit of the Holy Spirit Phi 2:8-11.

And they said, Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house. Act 16:31 We connect The Measure Of Faith that the Lord gave us at birth with the Gospel of Jesus Christ and we are born of His Holy Spirit and so become Sons Of The Holy Spirit.      Note that this verse does not tell us to believe on the Father, Son and Holy Spirit.     It tells us to believe on the Lord Jesus Christ who is:    → the Father    → the Son    → the Holy Spirit This is what Chrisitanity is all about - recognizing God in Christ Jesus so that we no longer flounder around in speculation and confusion.         → Jesus is the Way to God.         → Jesus is the Truth about God.         → Jesus is the Life of God.         → Jesus is God.

That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that the Lord hath raised him from the dead, thou shalt be saved. Rom 10:9 This is the encapsulation of Grace, clearly pointing out our part which is faith in Jesus and confession of Him as risen Lord and Saviour.      The implication of our part being to believe on Jesus Christ and confess Him as risen Lord, is that He has done everything else!      It is why we call it amazing Grace!      It is why the gospel is nearly too good to be true!      Who raised Jesus from the dead?      He raised Himself Joh 10:17,18 by His Holy Spirit Rom 8:11.

For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. Rom 10:10 It is Heart Faith that enables the miracle of the New Birth.      It is our personal confession of Jesus as Mighty God, Creator and loving Saviour that seals that miracle.

For we must all appear before the judgment seat of Christ; that every one may receive the things done in his body, according to that he hath done, whether it be good or bad. 2Co 5:10 The Judgment Seat Of Christ is the place where we come to understand and give account for that which we did in the name of Christ Jesus.     Some of it is good and some of it is bad.      This is kind of like a debriefing so that we understand more perfectly who Christ is and what the Gospel entails.      It is a fact that some believers will have been so messed up in their theology that they are saved as by fire - have no good works to show 1Co 3:15.

If any man`s work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire. 1Co 3:15 Rewards are one thing, salvation is yet another.     They are separate and disctinct.