CrossRoads:
Here is one way to do it.
Put your message in a large array.
Every 100mS, read out 32 bytes of the array and send it to the MAX7219.
Say 0 to 15 to start.
On the next 100mS, you move over 1 address in the array, and 1-16.
Then 2-17,
3-18,
4-19,
5-20,
and so on.
The array size is just limiteb by available SRAM.
Or, you can store it in PROGMEM for a larger array.
Or, you can store it in EEPROM, make your sketch fancier to allow changing it based on serial message received.
Lots of options.
but in this way the word flows on the led matrix? however I do not know .. there is no way using the library sprite?