You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Martin_Luther

Context:
The theologians, including Zwingli, Melanchthon, Martin Bucer, and Johannes Oecolampadius, differed on the significance of the words spoken by Jesus at the Last Supper: "This is my body which is for you" and "This cup is the new covenant in my blood" (1 Corinthians 11:23–26). Luther insisted on the Real Presence of the body and blood of Christ in the consecrated bread and wine, which he called the sacramental union, while his opponents believed God to be only spiritually or symbolically present. Zwingli, for example, denied Jesus' ability to be in more than one place at a time but Luther stressed the omnipresence of his human nature. According to transcripts, the debate sometimes became confrontational. Citing Jesus' words "The flesh profiteth nothing" (John 6.63), Zwingli said, "This passage breaks your neck". "Don't be too proud," Luther retorted, "German necks don't break that easily. This is Hesse, not Switzerland." On his table Luther wrote the words "Hoc est corpus meum" ("This is my body") in chalk, to continually indicate his firm stance.

Question:
What did Luther's opponents think that it meant about God's presence?

symbolically present