How do you expect your children to understand just how serious a matter you consider their absence from Mass if you resolve never to speak of it to them? Why do you assume that any statement of parental expectations is “lecturing”? Granted,
St. Francis of Assisi is believed to have said, “Preach the gospel always; when necessary, use words,” but that statement presumes that words sometimes
are necessary. And it was
St. Ignatius of Loyola to whom the adage is attributed, “Pray as if everything depends on God; work as if everything depends on you.”
Your children are at an age when many of their contemporaries are still in some ways dependent upon their parents (e.g., health insurance, college education, assistance with living expenses). If that is the case for your children, then it is appropriate for you to explain to them that your continued material beneficence is dependent upon their meeting their Catholic obligations. If they want to be entirely independent of parental authority, then they should be prepared to be so on their own dime. (And even then, independent adult children still owe their parents the respect of listening to and considering carefully their parents’ concerns for their welfare, whether or not they ultimately choose to follow through on parental advice.)
If you do not take seriously the responsibility to evangelize your own children, how could you possibly be able to evangelize anyone else (cf.
Luke 16:10-12)?