Absolutely, you have a right to your opinions, (and other things), under the First
Amendment. Millions of patriots will defend those rights, to the death. It is the Second Amendment that makes that possible for us ordinary Americans.Remember how our country was formed? Colonist rose up against tyranny and against all odds, defeated Great Brittain. They did this because they were armed at least equally against British troops.
The Colonial army was largely using rifles at the time. England and their Hessian guns-for-hire were still using muskets. (Rifles have greater range, more power and superior accuracy.) Today, the militia, (see US Code 1, Sec. 1) has semi-automatic rifles, while the armed forces, (I'm a USAF Combat Arms vet), have fully automatic weapons.
Today, the advantage of the citizenry is in numbers and the likelihood that many armed service members would not follow unlawful orders and side with The People. (After all, we took an oath to "uphold and defend the Constitution of the United States, against all enemies, foreign and domestic".) Therein lies the purpose behind the 2A; in addition to providing for one's personal protection, it is to discourage tyrants from trying to take power. (A government that fears an armed populace is a government to be feared.)
America has some 20K miles of border, it is crucial that the population be able to step up to defend it. No standing army could do so of its own accord. (The words of Japanese Adm. Yamamoto, "It would be impossible to invade the American mainland; we would find a rifleman behind every tree", speak to this truth.)
It is crucial to the preservation of our Constitutional Republic and the liberty that it provides, that the citizenry be prepared at all times for all contingencies.