“still today various Christian bodies and people repeat Peter’s mistake. They refuse to have fellowship with professing Christian believers unless they have been totally immersed in water (no other form of baptism will satisfy them), or unless they have been episcopally confirmed (they insist that only the hands of a bishop in the historic succession will do), or unless their skin has a particular colour, or unless they come out of a certain social drawer (usually the top one), and so on.
All this is a grievous affront to the gospel. Justification is by faith alone; we have no right to add a particular mode of baptism or confirmation or any denominational, racial or social conditions. God does not insist on these things before He accepts us into fellowship; so we must not insist upon them either. What is this ecclesiastical exclusiveness which we practise and which God does not? Are we more stand-offish than He? The only barrier to communion with God, and therefore with each other is unbelief, a lack of saving faith in Jesus Christ.”
The quotation above is taken from The Message of Galatians by John Stott, specifically his commentary on Galatians 2:11-16.