God wants us to know that He means exactly what He says. In prophecy, this means that it will be literally, completely, exactly fulfilled. He gives examples to show this in the Bible in cases where both the original prophecy and the later historical fulfilment is recorded.
In the days of the Kings of Israel, wicked King Ahab received word from God of his coming doom. The prophet Micaiah faithfully told Ahab on several occasions that he was in trouble for his wicked life, and Ahab hated him for it. As Ahab prepared to go to war against the Syrians in I Kings 22 Micaiah prophesied the end of Ahab in the coming battle. "And he said, I saw all Israel scattered upon the hills, as sheep that have not a shepherd: and the LORD said, These have no master" (verse 17a).
Now despite the prevailing "positive" attitude of all the other prophets that were more in the habit of telling the king what he wanted to hear, God's Word was literally fulfilled. Even though Ahab, himself went to battle disguised, while another man wore the royal robes, Ahab perished on the battlefield. Verse 34 (quoted above) tells us that a man shot an arrow in the air without even having a specific target. But the arrow of God's judgment had Ahab's name on it, and it found an opening in his armour to inflict a mortal wound.
The lesson here is that a God who can use such means to fulfil his word will always complete His purpose. "Be sure your sin will find you out" (Numbers 32:23). The sure fulfilment of the curse of God's law against law breakers was seen also by the prophet Zechariah as a flying roll (scroll) sent out by God to ensure punishment follows sin. "Then said he unto me, This is the curse that goeth forth over the face of the whole earth: for every one that stealeth shall be cut off as on this side according to it; and every one that sweareth shall be cut off as on that side according to it" (Zechariah 5:3).
The only way to escape the judgments of sin foretold in the Bible is by repentance of sin and faith in the Saviour, Jesus Christ.