pipe a program into less

Git is probably writing its output into standard error stream instead of standard output stream because command parameters are not correct. Please read about Unix standard streams here.

To fix the problem you have to redirect the error stream into output stream like this:

git config 2>&1 | less

Piping only redirects stdout. If you want stderr as well then you need to redirect that to stdout first.

git config 2>&1 | less