A simple key-shift cipher
You know what comprehensions are, which is good!
But you've a couple of problems:


str.join(',', text_shift) is abnormal and should probably be ','.join(text_shift).
str.split(text, ',') is equally abnormal and should be changed to text.split(',').
text_split = list(text) is unneeded, as you can loop thought the string the exact same way.
text_split = [ord(i) for i in text_split] can be merged into text_shifts comprehension.
You can change both cipher and decipher to be one-liners.


I'd also change both direction * shift to be a variable, just to ease reading of the comprehension slightly.

And so you should be able to end up with functions that look like:

def cipher(direction, shift, text):
    order = direction * shift
    return ','.join([str(ord(i) + order) for i in text])


def decipher(direction, shift, text):
    order = direction * shift
    return ''.join([chr(int(i) - order) for i in text.split(',')])




Finally, your module level doc-string should have a short description on the first line, and then optionally have two spaces and a longer description.

You used implicit string concatenation, but you kept using \ at the end of the line.
Instead I'd change you string to be wrapped in () to remove these.

I also disliked that you added your whitespace characters to the front of the next string.
It looks odd, and is easier to read/ignore when it's on the other line.

And so in all I'd end up with:

"""
Simple alphabetical cipher

This is a simple alphabetical shift encypter. Enter -1 or 1 for the direction,
your desired shift and laslty, the text to cipher.
   Written by Sami Dena (aurlit@riseup.net)
"""

def cipher(direction, shift, text):
    order = direction * shift
    return ','.join([str(ord(i) + order) for i in text])


def decipher(direction, shift, text):
    order = direction * shift
    return ''.join([chr(int(i) - order) for i in text.split(',')])


if __name__ == '__main__':
   string = ("The encryption step performed by a Caesar cipher is often "
             "incorporated as part of more complex schemes, such as the Vigenère cipher, "
             "and still has modern application in the ROT13 system. As with all single-alphabet "
             "substitution ciphers, the Caesar cipher is easily broken and in modern practice offers "
             "essentially no communication security.")

   encrypted_string = cipher(-1, 4, string)
   print(encrypted_string)
   print(decipher(-1, 4, encrypted_string))