Why should we be required to reply in Christian kindness to a man that is as much a liar and non-scholar as Dan Brown?
Because Jesus says so.....
Love for Enemies
27"But I tell you who hear me: Love your enemies, do good to those who hate you, 28bless those who curse you, pray for those who mistreat you. 29If someone strikes you on one cheek, turn to him the other also. If someone takes your cloak, do not stop him from taking your tunic. 30Give to everyone who asks you, and if anyone takes what belongs to you, do not demand it back. 31Do to others as you would have them do to you.
32"If you love those who love you, what credit is that to you? Even 'sinners' love those who love them. 33And if you do good to those who are good to you, what credit is that to you? Even 'sinners' do that. 34And if you lend to those from whom you expect repayment, what credit is that to you? Even 'sinners' lend to 'sinners,' expecting to be repaid in full. 35But love your enemies, do good to them, and lend to them without expecting to get anything back. Then your reward will be great, and you will be sons of the Most High, because he is kind to the ungrateful and wicked. 36Be merciful, just as your Father is merciful.
>>>Love your enemies<<<
Of course, if you love someone you will attempt to correct them from their evil ways to save them from eternal damnation, much as a good father uses a rod on the behind of a spoiled child to save him from a life of sin.
If that doesn't work, there is this one: "Resist the devil, and he will flee from you." -- James 4:7
Because Jesus says so.....
Indeed, and it bears repeating.