"Why does the Old Testament show
a God of wrath and the New Testament a God of mercy?"
The God of the New Testament
is the same as the God of the Old Testament. The Bible
says that He never changes. He is just as merciful in
the Old Testament as He is in the New Testament. Read
Nehemiah 9 for a summary of how God mercifully forgave
Israel, again and again, after they repeatedly sinned
and turned their back on Him. The psalms often speak
of God’s mercy poured out on sinners.
He is also just as wrath-filled
in the New Testament as He is in the Old. He killed
a husband and wife in the Book of Acts, simply because
they told one lie. Jesus warned that He was to be feared
because He has the power to cast the body and soul into
hell. The apostle Paul said that he persuaded men to
come to the Savior because he knew the "terror
of the Lord." Read the dreadful judgments of the
New Testament’s Book of Revelation. That will
put the "fear of God" in you, which incidentally
is "the beginning of wisdom."
Perhaps the most fearful
display of His wrath is seen in the cross of Jesus Christ.
His fury so came upon the Messiah that it seems God
enshrouded the face of Jesus in darkness so that creation
couldn’t gaze upon His unspeakable agony. Whether
we like it or not, our God is a consuming fire of holiness
(Hebrews 12:29). He isn’t going to change, so
we had better ...before the Day of Judgment. If we repent,
God, in His mercy, will forgive us and grant us eternal
life in heaven with Him.