Many things in this life are worth defending. We are to "fight hard for the faith" (Jude 3), defend truth (Sir 4:28), uphold the rights of the poor (Is 1:17), and make sure that the name of God is held as holy (Lk 11:2).
One thing we are not to defend is our own reputation. David was cursed viciously by a fellow Israelite as he fled Jerusalem in disgrace, having been deposed as king by his own son (2 Sm 15:14ff; 2 Sm 16:5ff). He did not defend himself or his honor. He didn't even explain that he had been wronged by his son. He accepted without bitterness the calumny of another as a chastisement which would ultimately be for his good (see Jb 2:10).
Jesus, the Son of David, took this humility a step further. "He humbled Himself" (Phil 2:8) and accepted the death of a criminal though he was innocent (Lk 23:32, 41, 47). Through it all, "He was silent and opened not His mouth" in self-defense (Is 53:7).
When we know God is our Vindicator, we can resist the temptation to defend our reputation. God intends to do a much better job of vindicating His children than we could ever do on our own behalf. In this Great Jubilee year, Jesus announces "a day of vindication by our God" (Is 61:2; see Lk 4:19). "This is the lot of the servants of the Lord, their vindication from Me, says the Lord" (Is 54:17). "He will make justice dawn for you like the light; bright as the noonday shall be your vindication" (Ps 37:6). "Your vindication shall go before you" (Is 58:8). Shout with Job: "I know that my Vindicator lives" (Jb 19:25).