Priests and some lay ministers are planning coordinated ceremonies blessing gay relationships in about 100 Catholic churches and other venues in Germany, including Essen Cathedral, over the next few days, most of them on Monday. Almost 20 events will be live-streamed. Such blessings have become common over the past decade in Germany and some other parts of Northern Europe, but they have usually taken place quietly, in places other than churches. Monday’s highly visible ceremonies will mark a protest against a Vatican declaration in March, approved by Pope Francis, prohibiting the blessing of same-sex relationships on the grounds that God “cannot bless sin.” “It always has been a little bit kind of a secret,” said the Rev. Christian Olding, a Catholic priest in the northwestern town of Geldern, who says he has blessed about 10 same-sex couples in the past eight years. “This is the first time that we are going this way in society, to do it visibly for everyone.”