‘Holding faith’, fidelity, loyalty, faithfulness to the truth, faithfulness to the cause of Christ. ‘Holding’, grasping, the Greek is strong, clinging in faithfulness to the cause, and a good conscience.
It is the same with every one of us. You need a good conscience, always ready to self-examine, to challenge yourself, to be challenged by others and take the challenge seriously.
No preacher can inflict an illness upon you; there are no apostles today. But it leaves on record the seriousness of playing games with the word of God, of becoming so proud we make it mean whatever we want it to mean, of chasing our own theories and ideas, instead of being subject to the entire word of God. It's impious. It's irreverent. It's appalling. But as for us, cling on to faith, faithfulness, and a good conscience, and be all out for the gospel of Christ.