If all men will be rewarded according to their works then is preaching the forgiveness of sins useless?

Those sentences which are colored in orange are from Maharishi Dayananda Saraswati book Satyarth Prakash (The Light of Truth) and those which are colored in black are Jerry Thomas’s response.

"And then he shall reward everyman according to his works." (16:27)

C. When all men shall be rewarded according to their works, it is useless for the Christians to preach the doctrine of the forgiveness of sins. If the latter be true, the former must be false. If the Christians say that those that deserve to be forgiven shall be forgiven, while those that do not deserve it shall not be forgiven, it cannot be right, since justice and mercy consist only in awarding punishment and for all works.

Answer: If Maharishi had at least read the paragraph as a whole, he would have understood that the people would be judged based on their acceptance of LORD Jesus Christ or not.

Matthew 16: 24-27 “Then Jesus said to His disciples, "If anyone desires to come after Me, let him deny himself, and take up his cross, and follow Me. For whoever desires to save his life will lose it, but whoever loses his life for My sake will find it.  For what profit is it to a man if he gains the whole world, and loses his own soul? Or what will a man give in exchange for his soul?  For the Son of Man will come in the glory of His Father with His angels, and then He will reward each according to his works. 

Further:

John 3: 16- 21 “For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life. For God did not send His Son into the world to condemn the world, but that the world through Him might be saved. "He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God. And this is the condemnation, that the light has come into the world, and men loved darkness rather than light, because their deeds were evil. For everyone practicing evil hates the light and does not come to the light, lest his deeds should be exposed. But he who does the truth comes to the light, that his deeds may be clearly seen, that they have been done in God." 

This renders the questions of Maharishi as invalid.