Atheism is religious in nature as much as Islam, Judaism, and Christianity. (Go back and read that sentence again carefully before you comment. I didn’t say “atheism is a religion.” I said “atheism is religious in nature.” My next sentence will explain what I mean).
Each posits certain beliefs about God, nature, and life which guide them as they seek to live their lives and guide the lives of others on the basis of and in accord with those beliefs. It is a belief structure that is inherently about religion (specifically, it is about why religion cannot be believed or is wrong or evil or whatever).
When, however, one forces such beliefs on others through legislation, personal attacks, or bullying, one is doing what is commonly termed “shoving your religion down my throat.” Simply holding to a point of view or practicing one’s belief does not constitute and shouldn’t be interpreted as “shoving religion down another’s throat.”
The political and societal agendas pushed by many religious people are also held and promoted by non-religious people (e.g., the sanctity of human life, the freedom to live and/or worship without government intervention and coercion, etc.) and may often reflect nothing more than a desire for the society and mores of bygone eras and previous generations. Thus, seeking to see these views reflected in law and in culture does not necessarily involve forcing others to hold to their religious beliefs.
The agendas of atheism and secularism, however, are almost always driven by their religious views. They are also almost always in the minority. So when atheists and secularists, who are sometimes as militant as some religious groups and more militant than many religious groups, promote their political agendas, they are in effect “shoving their religion down people’s throats” as much as any militant religious group.