If you are having problems with this part of the game, the best thing to do is to restart the "foy" game from the load games screen that takes you to waiting outside the church for your teammate to kick in the door. After the melee inside, instead of waiting for the officer to announce the German counterattack, head for the church steeple as soon as the Germans have been cleared from the loft area. This way, you will avoid the disruptive movement of the screen when the shells start hitting the church. You need as much time as possible in this scenario and starting to move to the church steeple before being told to do so will give you something of an edge.
Use the U.S. sniper rifle if you have it, or get the German one to the right of the ladder going up to the steeple.
When you reach the upper landing in the steeple, I recommend going into the crouch position in the opening of the wall - in this way, you expose less of yourself to fire from the gunners and their escorts. You can use the left and right movement keys to cover the entire field of fire. Another good way to protect yourself is to go prone when reloading, which you will have to do frequently.
The most important feature in this part of the game is the two telephone/power poles in the center of your field of view. All of the gunners gravitate to this feature because they can hide from you completely - this is the reason so many players have expressed frustration at not being able to see all of the gunners. While it is possible for the gunner to hide behind this feature and be completely invisible to you, he almost always leaves a minute part of his white uniform visible to you so that you can torment him by shooting the part that is exposed. When you do, he will leave his position of safety and you can then shoot him again. ALL of the gunners are drawn to this feature like a magnet, so what you need to do is to intercept them before they get there. After shooting the two or three gunners who are milling about behind the fence in front of you at the beginning of the action, you should then notice other gunners who come over the fence to the left and, especially, those who arrive down the road to the right. They will cross the road, jump the fence, and run like homing pigeons to the poles in the middle of the screen. Your job is to shoot them in the middle of the road to the right of your field of vision, or to try to shoot them as they bob and weave while trying to reach the poles.
Do not waste your time shooting anyone but the gunners and the machine gunner, unless you see that they are actually hitting you and your health is dropping. This uses up ammo and reloading causes you to use up time and to take your eyes off of the scene in front of you while you are prone.
Shoot the machine gunner first if he has appeared and then start shooting the Panzerschreck gunners along the fence to your front. Check for a new machine gunner every few seconds (using the default setting with the right mouse button to toggle the telescope view is the best way). Do not get so caught up in shooting gunners that you forget about the machine gun, because if he gets a bead on you, you will be dead in a matter of seconds. If he does start shooting at you, and you notice your health disappearing at an astronomical rate, go prone immediately. He will lose interest in you after a few seconds, at which time you can go back into a crouch and shoot him when his attention is diverted (if this happens, and you have time, remember the 50 units of health behind you). Remember that another machine gunner reappears within a short time after you have shot his predecessor, so don't fixate on the Panzerschreck gunners and ignore him.
After clearing out the gunners who are lined up on the fence at the beginning of the play, most of your attention should be on the road to the right of the fence because that is where the reinforcements are coming from.
Forget all that jazz, after you give the beat down on all those Krauts inside the building, take the mg34 that the one guy had and position yourself in a spot at the top that you can see both sides of the building. Also have either the garand or the gewehr with you so when you run outta ammo with the MG34(which you probably will) you can pick off the rest.
Tip: only hit the guys with a panzershreck on them.