The Gospel can never be preached without consequence of ultimatum! And the presentation of the Wrath of God is not optional but mandatory, not suggested but required. But know this that the Wrath of God is never intended to scare sinners into salvation (for fear is never a proper motive for salvation), but is always there to condemn those who will never come unto salvation.
For God has so prepared His message for both groups of hearers, seeing that the preaching is done before a mix of those that are to come and those who are to turn away. And it would appear that the Gospel preached in its entirety must have both ingredients within to be the one and only true Gospel.
Therefore it makes no difference whatsoever how well one presented the truth of God's Mercy, for if he did not present alongside of it God's Wrath, the Gospel complete was not preached.
What are the effects of only preaching a message where the Mercy of God is lone presented? The effects are tremendous, in that what we fail to see is something revealing about the Wrath of God. For where God's Mercy is presented as the only part of salvation, it is here where we will find both believer and unbeliever alike coming forth to receive what only the one could ever receive. And it's the Wrath of God that reveals in truth the true believer. Because it's something that's tied to the unbeliever that this Wrath of God brings out from within.