Adam Clarke on 1 Corinthians 3:4

For while one saith, I am of Paul, etc. - It was notorious that both Paul and Apollos held the same creed; between them there was not the slightest difference: when, therefore, the dissentients began to prefer the one to the other, it was the fullest proof of their carnality; because in the doctrines of these apostles there was no difference: so that what the people were captivated by must be something in their outward manner, Apollos being probably more eloquent than Paul. Their preferring one to another on such an account proved that they were carnal - led by their senses and mere outward appearances, without being under the guidance either of reason or grace. There are thousands of such people in the Christian Church to the present day. See the notes on 1Cor 1:10, etc.