The Jews in Nazi Germany still had a right to life & liberty the fascist regime of Germany simply suppressed them.
The right didn't go away. The rights preexisted Nazi Germany and outlived it and rely on no such government for their existence.
The right we enjoy today are not created or granted by the Constitution but rather protected by the Constitution. The founders being far from wide eyed idealists realized the governments often do suppress the exercising of rights. They wrote the bill of rights to appease those who were concerned of a new tyrannical govt would replace the old tyrannical govt and also to make it MORE DIFFICULT (but obviously not impossible) for the government to suppress rights.
The Constitution & Bill of Rights aren't magical. If tomorrow the United States formed the Church of American and made all other forms of religion illegal the Constitution by itself can't stop that. The suppression would be UNCONSTITUTIONAL and the Judiciary and military having taken an oath to defend the Constitution have an obligation to act but if they don't it would happen.
The Bill of Rights serves two purposes.
First it makes it difficult for the government to suppress rights without being tyrannical and risking backlash from the populace. Second it indirectly protects liberties by codifying the rights so that future generations would know and understand them thus preventing tyranny from getting hold by electing Representatives who share their same values. This second aspect has died a little as it required an informed populace.
So what is the defining line between lawful suppression and unlawful suppression of rights (including RKBA)? "strict scrutiny" is the tool used to ensure the government is not prohibited from serving a compelling government interest (such as public safety). The courts have long held that rights are not absolute and can be restricted. To avoid them being restricted to the point of uselessness a 3 prong test has emerged.
http://en.wikipedia.org/wiki/Strict_scrutiny
To pass strict scrutiny, the law or policy must satisfy three prongs:
First, it must be justified by a compelling governmental interest. While the Courts have never brightly defined how to determine if an interest is compelling, the concept generally refers to something necessary or crucial, as opposed to something merely preferred. Examples include national security, preserving the lives of multiple individuals, and not violating explicit constitutional protections.
Second, the law or policy must be narrowly tailored to achieve that goal or interest. If the government action encompasses too much (overbroad) or fails to address essential aspects of the compelling interest (under-inclusive), then the rule is not considered narrowly tailored.
Finally, the law or policy must be the least restrictive means for achieving that interest. More accurately, there cannot be a less restrictive way to effectively achieve the compelling government interest, but the test will not fail just because there is another method that is equally the least restrictive. Some legal scholars consider this 'least restrictive means' requirement part of being narrowly tailored, though the Court generally evaluates it as a separate prong.
1) Compelling government interest
2) Narrowly tailored
3) Least Restrictive Means
The antis always look to prong number 1. no doubt public safety is a compelling government interest. However they fail to even consider points two and three.
Banning all guns WOULD serve a compelling government interest however it is not the least restrictive method to accomplish that interest and it certainly is not narrowly tailored.
Suppressing gun rights for life without appeal or exception is not the least restrictive method, instead something like 10 year period followed by appeal works and is less restrictive and accomplishes the compelling interest.
Suppressing all felons rights IMHO is not narrowly tailored enough. Many felons are no more dangerous than those not convicted of a felony. The compelling interest can be achieved by suppressing the rights of violent felons a much narrower definition.
<On edit: added the word exercise as in "suppress the exercise of those rights" to clarify. Thanks iverglas. Fixed million spelling errors and clarified some points>