You need to stop repeating the doctrine of men and actually read what has been written. See #7.
I don't consider Paul's words in 1 Cor. 12:13 to be doctrine of men:
"For by one Spirit we were all baptized into one body, whether Jews or Greeks, whether slaves or free, and we were all made to drink of one Spirit."
Paul was speaking to the Corinthian believers ... and he says they were ALL baptized into one body ... that can only be true if spirit baptism happens at conversion.