Baby skin.

Naaman was a man of war, a general over thousands of troops, and the king's right-hand man in military affairs of the state. Yet, he was leprous. All the world's power and material wealth mattered little to this man, if he had to live like an outcast because of his condition. Leprosy, like modern-day cancer, was incurable by medicine. What he needed was a miracle, and he indeed obtained one from the God of Israel! Though one outside of the Abrahamic covenant, God still ministered to Naaman's need, and glorified His Name in the process.

What impressed me rather, was the extent of his healing. God could have just restored his skin to health, but no, He did not. Instead, He went one step further. We forget that Naaman was a man of war, and how can such a man have no scars on his body? Yet, God was glorified that day and for every day that the army of Syria saw their commander, because in Naaman's perfect baby skin, they saw not just a God who heals, but One who has power to restore to pristine form. Through one man's affliction and subsequent healing, Syria received word that God was not just powerful, but they could worship Him too.

So [Naaman] went down and dipped himself seven times in the Jordan, according to the word of the man of God, and his flesh was restored like the flesh of a little child, and he was clean. - 2 Kings 5:14

Discounting the power of God.

I don't know if you've heard of the Gospel being compared to the cure for cancer, and how it shouldn't be kept only to a select group. Following that line of thought, if the Gospel is truly the solution for the cancer of sin that has stricken the human race, its power to mend and heal should be the chief part of its message. No doctor promotes a medicine based on its taste, but on its effectiveness in curing the patient of his or her condition. Similarly, no Christian should tote the Gospel as mere Prosperity, but to convey it with all of its intended power - to restore a fallen soul to a purposeful and fruitful relationship with its Maker.

No medicine is proved effective till it cures someone, and neither should the Gospel. Therefore, how can the Gospel be preached without the power of God? If preached without power, it will only serve as a good tale to share over a drink. If preached with power, seen through a living testimony, it will indeed be good news to the hearer. Therefore, if you profess that Christ is Lord and Savior, preach the Gospel with power, not just clever speech. Remember, not a single one of the apostles failed to walk in the power of God while they lived and breathed on earth, fulfilling the Great Commission. 

"For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek." - Apostle Paul to the Roman church in Romans 1:16