Yes, there are scared placed for people to worship without being murdered. In fact, the French Church is sacred. The fact that someone committed a criminal act there does not mean that the church is not scared to the overwhelming majority of people; it only takes one person to commit a criminal act.
Hate does not respect sacred spaces. When the children in the daycare in Birmgham Alamaba were murdered by a bomb, the bomber did not respect that this sacred space was part of a church. Unfortunately hate is not prevented by churches or other sacred spaces. All we can do is fight back with love.
There is no where sacred that can guarantee a person will not be murdered while they are worshiping. Sacred ground is only sacred for those that believe in the power it holds. No corner of the Earth is safe from ill intent, and no church or other holy place cant guarantee a person's safety.
Given the outbreak of terrorist attacks, we have to assume that no place is 100 percent safe, including places of worship. We have to be extra vigilant these days, but not allow fear to stop us from living our lives. Terrorism exists to evoke 'terror'--if we let it paralyze us, the terrorists have accomplished their goal.