I have not read the homily and so cannot comment on it, one way or the other.
As to the general issue though, even were it morally justified to withhold taxes from the government, it would be prudentially unwise for anyone to do so – particularly if that person was responsible for the support of a family that would be adversely impacted by the financial and legal consequences of such a decision. If someone who is not married and not responsible for the temporal welfare of anyone but himself should choose to do so, it is his prerogative to face the consequences for such an action; but he should not attempt, on his own authority, to bind anyone else’s conscience to follow his lead.
It should also be said that an individual is not responsible for how an entity to which he must pay money chooses to spend his funds. He is paying solely for the benefits he needs from that entity; how his money is used is the responsibility of that entity. So, for example, if you pay taxes to the government, you are meeting a legal obligation and are receiving the just benefits derived from those payments in return (e.g., education, the maintenance of common resources, law enforcement, firefighting, etc.). If legally-elected or duly-appointed representatives of the government choose to spend your taxes to pay for intrinsic moral evils such as abortion or embryonic stem-cell research, the moral responsibility for those intrinsic moral evils resides with them.
