@Rickoshay75,
"Should we be afraid of another Terrorist attack?"
No. If you let your fear of a future attack curb your life then they win. You constantly turn yourself into a victim repeatedly but by your own doing. You can't let their actions change you.
Although these events happen, they are heightened by the way information is being moved and people are so quick to jump on them. They get splashed all over social media sites because it draws in viewers and viewers equals ad revenue. Then on the flip side groups are quick to try and push their agendas through either the victims or the perpetrators.
I doubt we will ever be free from such things. With a global population of over 7.5 billion there are bound to be mentally ill people among us who will do things against others for what ever reason. This includes religious people attacking non-believers.
No matter what legislation we try to pass or laws we force upon people these things will occur because a person bent on causing someone else harm doesn't care what the laws are.
The only way to minimize these things is through proper education and it's on all levels. Parents raising their children with proper guidance and not indoctrinating them or ignoring them. People need to learn that not everyone is going to agree with you and their opinions might offend you but that doesn't give you the right to murder them because they don't believe the same thing you do.
The problem is mental illness and lack of education. So the solution is getting the treatment and education necessary to those people so they don't act out later in life.