“[The undeserved kindness of God] trains us to reject ungodliness and worldly desires and to live with soundness of mind and righteousness and godly devotion amid this present system of things.”
~Titus 2:12

Paul mentions soundness of mind three times in his letter to Titus, as well as alluding to our use of reason. (Tit. 1:8; 2:5; 3:2)
It seems to be the underlying theme of his letter.
He says that for someone whose mind and conscience are defiled, “nothing is clean,” right before he condemns religious hypocrisy. (Tit. 1:15,16)
We can conclude, then, that in order to have a stronger sound mind, we need to continuously nurture our own moral thoughts so as to have purer motives.
A Christian with a sound mind is one who adopts Christ’s way of thinking over his or her own. (Matt. 6:33,34; Rom. 12:2; Phil. 1:9,10; 4:4-7; 1 Pet. 4:7,8)
If we feel this world is pushing us toward our tipping point, we can meditate on the transcendence of God’s promises. (Tit. 1:2)

“[…] You may have him back forever, no longer as a slave, but as more than a slave, as a brother who is beloved […].
~Philemon 15, 16

In his letter to Philemon, Paul entreats him to welcome back their fellow Christian, Onesimus, as a brother more so than as an escaped slave.
Paul did not use his authority in the congregation to promote personal opinions on civic matters.
Instead, he appealed to his friend’s love for God and others. (Phil. 9)
Even today, in such a hate-filled world in which we feel the effects of generations of injustice, we can trust that divine love is capable of eradicating the root causes of inequality. (1 John 4:21)