Type the passage in Greek — the checker highlights every character
On a phone or tablet: install the free
Hoplite Polytonic Greek Keyboard
(Android
· iPhone/iPad).
Here is what it looks like when you activate it on your phone:

(A hoplite was a heavily armed infantry soldier of ancient Greece,
typically a citizen-soldier who fought on foot in close formation
(the phalanx), equipped with spear, large round shield, helmet, and body armor.)
On a desktop: turn on PC Keyboard mode below
and type using your regular keyboard — letters convert to Greek as you type.
Here is what the keyboard will look like on your phone:
"Blessed is the man who has not walked in the counsel of the ungodly, nor stood in the way of sinners, nor sat in the seat of scoffers; but his delight is in the law of the Lord, and in his law he will meditate day and night. And he shall be like a tree planted by the streams of water, which yields its fruit in its season, and its leaf does not wither; and whatever he does shall prosper."
Language-learning research suggests that people who TYPE Greek will learn faster than
those who merely look at Greek on the screen. But people who HANDWRITE Greek will learn even faster than those
who type it.
If you have a touch sensitive laptop screen or a phone, use a stylus or your finger to write out the passage.