"Now consider this, ye that forget God, lest I tear you in pieces, and there be none to deliver."
"Kiss the Son, lest He be angry, and ye perish from the way when His wrath is kindled but a little."
"Fear Him Who is able to destroy both soul and body in Hell."
"He that believeth not the Son shall not see life, but the wrath of God abideth on him."
"The wicked shall be turned into hell, and all the nations that forget God."
How do these promises show the love of God? By the simple fact that they are in Scripture at all. God didn't have to give any warnings to us. He could have thrown us all into Hell forever, without a word to us, and He would have been just in doing so. These promises are His warnings of love to us, that we might enter in at the strait gate. God must reward sinners for their sins because He is just. He cannot simply "forget it". Every sinful thought, word, and deed must be rewarded with its wages - "the wages of sin is death" - or God Himself would be unrighteous.
The promises we usually think of are much nicer to read, but we cannot come to those until we see the ones above. There is no appreciation of "Believe on the Lord Jesus Christ and thou shalt be saved," unless we first see God's wrath against us, and His just assessment of our character. Since God is holy, absolutely holy, and we are absolutely sinful, He WILL tear us to pieces and there WILL be none to deliver, without the deliverance that He Himself prescribes:
"Behold the Lamb of God Who taketh away the sins of the world."
"Whosoever believeth in Him should not perish, but have everlasting life."