Mercy cannot exist without wrath
The perfections of God are not in conflict with each other.
The entire Christians religion rests on love and mercy. God is justly displeased for our sins, and eternal wrath is waiting for us. But then God sent His only begotten Son to die on a cross. Jesus Christ took the punishment for our sins, and we have salvation because of His sacrifice. But that mercy is meaningless without God's just wrath against our sins.
The problem with those Christian pastors, speakers and authors who focus only on Christ's mercy is that they are downplaying His other attributes, such as holiness and justice. And whether intentionally or not, it sets up a false dichotomy with the Old Testament. The Psalms are filled with hundreds of examples of God's kindness and mercy. The book of Jonah demonstrates God's compassion for the wicked city of Ninevah, including the livestock in the city. Jonah was enraged that God was merciful to Ninevah.
Yes, God is loving and merciful, and calls us to believe on His Son and be granted eternal life. He is also holy and righteous and will pour out His wrath on sinners. Jesus was the meek and mild Prince of Peace, and He used a whip to violently drive the money changers out of the Temple - twice. Jesus is humble of heart, and he is the King of Kings who has been granted all authority in Heaven and on Earth. None of these virtues are in conflict with each other.
But because we humans are flawed, it is always our temptation to respond to one error by falling into the opposite error. It is our temptation to develop an "all or nothing" mentality. But this is not what Scripture teaches. People who are depressed and burdened by sin and guilt need to be told of God's love and mercy, but a world that is shameless needs to be told of God's righteousness and His Law. It is our wickedness that merits His wrath and makes His mercy necessary in the first place.