I was reading "As A Southern Jew..." and wondering why you complain when you know that the computer class is at a church. What really upset me though is that you make the case seem like Jacob's getting mixed messages.
On the one hand, you wanted to, frankly, be an antimissionary within a church. If, for instance, Jews For Jesus were at a technology camp at a JCC, I'd get the "Stop it!...Stop it NOW!" But at a church? You went as far as entertaining the idea of frankly doing something borderline close to what Donin and Christiani did. On the other hand, you made Jacob feel like you'd be mad at him for living out the values with which he is being raised. Jacob will certainly have a hard-enough time living the South if he keeps getting mixed messages from within his own family.
By the way, he'll also have a hard time if he learns that projection is acceptable. For example, you said that you thought that you heard something other than, "Do you want juice?" Maybe a sentiment about people whom you don't want to be around is manifesting itself in your thoughts and actions in ugly ways. As Jayne said, don't take Jacob to places where Jesus will be brought up if you don't want to hear about Jesus; and I add, don't hang around Christians if you don't want them around.
I also hasten to add that sending children mixed messages and teaching children "Hate thy neighbor and project thy hatred on thy neighbor" are not Jewish values—and certainly not, contrary to what Donin and Christiani taught, ones that Jesus taught, regardless of what one makes of him.