Must is literally “it is necessary” (Good News Translation). Be silenced translates an infinitive of the verb that literally means “to put something over the mouth” and is used figuratively to refer to preventing someone from talking. They must be silenced may be misleading, since this expression is often used to refer to killing someone, which of course is not Paul’s intention at all. “You must stop them from talking” would be a more satisfactory way of expressing the meaning (compare Good News Translation “it is necessary to stop their talk,” Contemporary English Version “you must make them be quiet”). One may also say “You must stop them from talking this nonsense.”
The reason for stopping these rebellious people from talking is that they are upsetting whole families with their teaching. For families see the same term translated “house” in 1 Tim 3.4. Upsetting comes from a verb that refers to the act of causing problems with regard to someone’s faith or beliefs; hence “to undermine someone’s faith.” See further on 2 Tim 2.18. Here the damage is done not only to the faith of certain individuals but to the faith of whole families, which indicates that many families are involved, and the problem has affected every member of each one of these families. The problems may have included disunity and conflict in families where not all the members become believers. But primarily the problems are related to their faith; that is, these problems tend to undermine their loyalty to the Christian faith and its message. In this light, upsetting whole families may thus be expressed as “they are causing all the members of some families to stray from the true message” or “… to falter in their faith.”
The way they have done this is by teaching what they have no right to teach. This last expression conveys the idea that something has happened that should not have happened, so Good News Translation “teaching what they should not,” Phillips “teaching what they have no business to teach,” New International Version “teaching things they ought not to teach.” But they teach these things for base gain; for this last expression see Titus 1.7, where the Greek forms one word by joining these two, translated “greedy for gain.” The whole motivation for their actions is financial profit, as Good News Translation makes clear (“and all for the shameful purpose of making money”).
An alternative translation model for this verse is:
• You must make them stop talking such nonsense, because they teach things which they shouldn’t, and so cause all the members of some families to doubt the true doctrine. They do this simply for the shameful purpose of making money.
Quoted with permission from Arichea, Daniel C. and Hatton, Howard A. A Handbook on Paul’s Letter to Titus. (UBS Handbook Series). New York: UBS, 1995. For this and other handbooks for translators see here .