Please submit sites which deal with theological (sytematic, exegetical, liturgical, or practical) contrasts and conflicts between the Christian Church and non-Christian bodies from a Lutheran perspective. Intra-Church and intra-Lutheran contrasts and conflicts are part of Polemics and should be submitted to that category.
While contemporary understanding of an apology is that of expressing sorrow over something done wrong, in Christian theology it involves the traditional meaning of a defense, specifically against the attacks of non-believers. The "apology" is normally a rationally constructed, fairly detailed statement.
Thus, Apologetics is often considered a "scientific" vindication of Christian truth against unbelief. While Lutheran theology does not allow for an absolute proof of God, it can and does argue contra other beliefs, and tries to do so through rational application of Scripture and the Lutheran Confessions.
As Apologetics guards the door to the outside, Polemics looks within. It is the discipline which addresses error inside Christendom. In Lutheranism, this is sometimes directed toward different churches and at other times toward those within Lutheran circles who are perceived by other Lutherans as being in doctrinal error.
Related in some minds is what is known as Comparative Religion, which involves a side-by-side look at different belief systems. Some think of it as the science of religion, others place it between the history and the philosophy of religion. It is not a traditional part of Lutheran theology, however, since it often tends to be value-neutral in its comparisons, while Apologetics and Polemics are, by nature, biased toward what is believed to be the best or the only true belief.