There has been a cross on the mountain by Orihuela since 1411. The Cruz de la Muela has therefore been a part of the historical, religious-and cultural heritage of the city for over six hundred years. It is as much a symbol of the city as it is a religious monument.
However, two lawyers from Murcia thought that it should be taken down and took their case to court. The grounds for the case rested on its incompatibility with a modern secular state. They first went to the Superior Court of Valencia and lost. Then they took their appeal to the Supreme Court and lost again.
A similar appeal in 2013 to remove the statue of Christ on the hill at Monteagodo was also rejected.
Since the Reconquista which ended with the fall of Granada in 1492, Spain has been a predominantly Catholic, Christian country. Although it is correct other religions should be allowed their freedom to worship as they see fit in what is now a non-secular country, that does not give them the right to change the very nature of where they live.
Actually, I very much doubt that the case was brought about because of an objection by any particular religious group but I might be wrong.