Matthew 10 :16 – “Look, I am sending you out as sheep in the midst of wolves. Therefore be wise as serpents and innocent as doves.”
What does it mean to be as wise as a serpent?
When a serpent is attacked , it is willing to have much of its body severed, as long as its saves its head. So to be as wise as a serpent means to be willing to lose everything: your wealth, your reputation, your friends, as long as you save your faith. Your faith is your head, by which you learn all truth, and by that truth your soul is set free.
We should , however, recognize that the wisdom of the serpent is not enough, we must be as honest and as innocent as doves. Indeed it is the combination of wisdom and innocence that creates virtue.

Above : 11th-century conch mosaic of John Chrysostom from the south-east apse of the nave of the Hosios Loukas monastery – source Wikipedia
The person who is wise as a serpent can sustain the most terrible attacks and still continue to flourish as a disciple of Christ. The person who is innocent refuses to retaliate against those who make the attacks. To be as innocent as a dove means never to take revenge on those who wrong you or undermine you.
Unless wisdom is tempered by innocence , one attack provokes another, and conflict continues without end. Unless innocence is tempered by wisdom, a person is so vulnerable that he will not even survive a single attack.
Rest assured that no one can take away your faith, your wisdom guard against that. But be careful never to bear a grudge against anyone who does you wrong.
Saint John Chrysostom