How can I resolve Git merge conflicts visually?

You can use a visual merge tool like diffmerge. You would use the same command to git visual diff except that you use git mergetool instead of git difftool.

git config --global merge.tool awesometool
git config --global mergetool.awesometool.cmd "path/to/awesometool --merge --result=\"$MERGED\" \"$LOCAL\" \"$BASE\" \"$REMOTE\""
git config --global mergetool.awesometool.trustExitCode true

References

http://stackoverflow.com/questions/585844