From what I've seen, nobody has responded to this question yet:

He said all children, there [in Germany], from kindergarten through 4th grade, have to attend religious instruction classes during their school day. According to him, they have a choice of Roman Catholic or Lutheran. His son was prepared, in school, for his first communion by the local priest. When asked what a person was supposed to do if they were Jewish, he had no answer, except that a better question might be what to do if one is Muslim, as they have so many immigrants.

I would like to hear from some of you who live in Germany, if this is true, please.

That's a mixture of true and false and a central assertion (have to) is false.

There is religious instruction in the curriculum of all German schools (after kindergarten) but it is the only part of the curriculum that is not compulsory (for a qualification see below). Until a kid is 14 years old it is her parents choice whether she has to attend or not, from 14 on it is her choice.

Due to the relative proportion of catholics/protestants the usual classes offerend will come from these two faiths. With a strong enough minority from another religion there can be classes for other religions as well.

In some lands (parts) of Germany, pupils that do not go to religious instruction have to attend a class on 'general ethics' (or some other fancy name) in which thry are e.g. taught about ethical questions from different point of views, among them religious.

Wolfgang