This is a challenge where you have to spend 20 min a day for 21 days to complete all the Gospels in New Testament.
It takes 21 days on an average to form any habit. So once you form the habit of reading Bible, you can continue the remaining on your own
4 Gospels has 82,590 words. In 20 min average person can read 4,000 words. So in 21 days you can complete all the Gospels.