The problem with what you are saying is that even if a backdoor could work technically, and it was actually used effectively by the authorities (the Paris attackers communicated over unencrypted media), it STILL would not do anything to "keep people safe".
130 people were killed in those attacks. 361 people died in automobile accidents in Minnesota in 2014, to find a random statistic. Terrorism is simply not a real threat, and eliminating it will not make anyone any safer.
While not a "we should live in fear" level threat (or even a "take off your shoes at the airport" level threat) terrorism is certainly a real threat. I do want the government investigating and dealing with that threat. That being said, the threat is not immediate enough to warrant the infringement of our basic rights.
130 people were killed in those attacks. 361 people died in automobile accidents in Minnesota in 2014, to find a random statistic. Terrorism is simply not a real threat, and eliminating it will not make anyone any safer.