I can't even bring myself to use this term myself, so yes I do find it offensive. The thing is for many religious groups and leaders this term is taking God's name in vain. There are certain words and terminology that people just don't want to hear because they are offensive. So, regardless of what our own personal feelings maybe we need to still be sensitive to others around us and what they feel is improper terms and words.
While not all citizens believe in God, or practice christianity, it is still disrespectful and offensive to refer to an object, no matter how groundbreaking and incredible, as the "god" particle or "goddamn" particle. For Christians, God is a scared symbol, and is considered to be something not of this earth. To refer to an object by the same name is to insinuate that God is less than a higher being, and is therefore disrespectful to the belief of Christians.
The Higgs boson particle is an elementary particle in The Standard Model of particle physics. Therefore, It usually takes a non-zero constant value everywhere. the particle should have a scientific-sounding name. This elusive particle has been called the God particle. Perhaps the name of the particle could be shortened or abbreviated in a scientific-sounding way without religious reference. Evidence for its existence is hard to obtain, that is why the unusual name of "goddamn" has been given to it, as though this particle makes you want to curse in frustration. It is offensive when compared to the term God particle.
No, the name "the God particle" is not offensive to religious individuals. The term "God" is a concept that doesn't belong to people of any one religion. It is my belief that any group of people can use the term "God" to refer to anything that they regard as a creator.