Kill a Stalker with the Seeker Rifle while zoomed in. Take all the items you can carry, as you will get back into the hallway adjacent to the church lobby (and hence, the gift shop) shortly. There's a save station (due to the QTE death-scene), so save if you like. Stasis the slamming door and get into the security office. Schematic - Security Suit in the office storeroom near the hatch. The necromorphs will appear once you step outside.

Insert the circuit to unlock the door across the room. Solve the door puzzle by pulling open the panel near the dead guy in the mind-wipe machine and taking the circuit module to the circuit panel by the door. You can either use a Javelin Gun to put down a spear (right under a vent or in the middle of the rooms is good) or simply juke/Line Gun or Plasma Cutter the suckers with some stasis. There's a reason for this, as two elite Slashers will drop in and attack soon after Isaac solves the puzzle to the locked door. Proceed to the brain-washing center and note the very large blow-out window in the room. Note you can break the fuse to unlock the door back to the church lobby (and hence the enemy free gift shop) to save, shop and upgrade. Smash through the enemies down to the ground floor and ride the elevator up to exit. Necromorph infectors will animate some corpses and march them upstairs you can trigger the spawn and use the long curve of the walkway to delay them this lets you shred some upper limbs. Head across the church lobby to the other wing of the facility. Yank the node to you from the corner, and you avoid fighting the elite Slasher that appears above the desk.

Remember the kinesis trick to bring items to Isaac to avoid being ambushed. Power Node - Reading room near the gift shop. After each jaunt into the church, you will be able to open doors that lead back to the gift shop so you can save, etc. The gift shop is the 'safe room' where Isaac can save, shop, and upgrade weapons.

The first thing to do upon enter the Church of Unitology is to locate the gift shop.

Dead space 2 walkthrough chapter 9