John 6:10-14 New American Standard Bible (NASB)
Jesus said, “Have the people sit down.” Now there was much grass in the place. So the men sat down, in number about five thousand. Jesus then took the loaves, and having given thanks, He distributed to those who were seated; likewise also of the fish as much as they wanted. When they were filled, He said to His disciples, “Gather up the leftover fragments so that nothing will be lost.” So they gathered them up, and filled twelve baskets with fragments from the five barley loaves which were left over by those who had eaten.
The Feeding of the 5,000 is also known as the "miracle of the five loaves and two fish" given that the Gospel of John reports that five barley loaves and two small fish supplied by a boy were used by Jesus to feed a multitude.
X is the Greek letter “chi,” the initial letter in the word Χριστός. And here’s the kicker: Χριστός means “Christ.” X has been an acceptable representation of the word “Christ” for hundreds of years. This device is known as a Christogram.
X is also used to denote multiplication.
Hence "XX" for Christ Multiplies :)