Is it useless to serve God? (Malachi 3:13-18)

"Your words have been harsh against Me,”Says the Lord,“Yet you say,‘What have we spoken against You?’You have said,‘It is useless to serve God;What profit is it that we have kept His ordinance,And that we have walked as mournersBefore the Lord of hosts?So now we call the proud blessed,For those who do wickedness are raised up;They even tempt God and go free.’ ”Then those who feared the Lord spoke to one another,And the Lord listened and heard them;So a book of remembrance was written before HimFor those who fear the LordAnd who meditate on His name. “They shall be Mine,” says the Lord of hosts,“On the day that I make them My jewels.And I will spare themAs a man spares his own son who serves him.”Then you shall again discernBetween the righteous and the wicked,Between one who serves GodAnd one who does not serve Him (Malachi 3:13-18).