The Greek word for “heaven” is ouranos (oo-ran-os’) meaning (a) the visible heavens: the atmosphere, the sky, the starry heavens, (b) the spiritual heavens.
In the context, this verse is referring to Jesus’ prophecy about the end times in the future. His Word is so sure to come to pass that the sky, space and the spiritual realm will pass away first before one single letter of His Word fall to the ground. In John 1:1 Jesus is called The Word because He is the expression of God’s character. Revelation 19:13, Jesus is called the Word of God signifying that not only is He expressing God’s character but that He is Eternal “I AM” and the whole message of the Bible funnels to Him.
If anyone denies the inerrant Word of God claiming that the scriptures have errors, he is admitting that Jesus is not perfect since the Word and Jesus can’t be separated. The only one recorded attacking scripture is Satan in Genesis 3:1 Now the serpent was the most cunning of all the wild animals that the Lord God had made. He said to the woman, “Did God really say, ‘You can’t eat from any tree in the garden’?” Should anyone come to you and say that the scriptures we have today has 1-5% errors, that person is not from God but from Satan to destroy your trust in God’s Word and to kill you spiritually. Don’t believe him but believe what Jesus said. Satan wants to attack the Bible so that you won’t get stronger through the Word. Once you doubt it, you won’t read it hence leading to spiritual starvation and destruction. Matthew 4:4 But He answered, “It is written: Man must not live on bread alone but on every word that comes from the mouth of God.”