Contradiction with Acts 15:36-41
Galatians 1:2 mentions "all the brethren which are with me," suggesting harmony among Paul and others, but Acts 15:36-41 describes a sharp disagreement between Paul and Barnabas, showing division among early Christians.
Acts 15:36-41: And some days after Paul said unto Barnabas, Let us go again and visit our brethren in every city where we have preached the word of the Lord, [and see] how they do.