Alright, so how competitive are you thinking you want to be? You have some good elements in the list (fire raptor, predators) and some fairly lackluster elements (bolter chosen, bikes)
On the subject of cultists. Their job isn't to survive, but large screen units (20+ models in unit), are critical in Three roles.
1. To block charges.
2. To fill space to disrupt deepstriking units (stop T1 charges into valuable units).
3. Soak up smites for a turn or two.
Combi-Bolter chosen are just really terrible for the cost, and Cultists would be a much better investment for the above three reasons. Smite doesn't care about your armour save, and if something is going to kill 10 cultists, it'll kill 5 power armoured marines too, you might as well save the points.
Your army is also very static and slow. You need mobility to get to objectives in order to win games, or chase down folks.
The top armies in the game right now are (in no particular order).
1. Hive Tyrant spam (4-6 flying hive tyrants with support
2. Pox walker spam Death Guard (with an invincible wall of pox walkers)
3. Plauge Burst crawler spam Death Guard
4. Tzzangor Enlighted bow spam (70-80 Enlighted with support)
5. Ynnari Dark Eldar/Shinning Spear spam.
You can see the top 16 army lists from Adepticon (last big event) here.
So, you should try to build your list in a way that you can beat, or compete agaisnt these sorts of lists.
Big blobs of Slaanesh Cultists are amazing, as you can pop 'vets of the long war', and the shoot twice strategem and then fire 120 shots (from a 30 man unit with autoguns), which get +1 to wound. Which means they'll wound nothing in the game worse than a 5+. It'll eliminate units, especially if you spent the CP to remove the unit from the board, redeploy at full strength from any table edge, and then shoot.
Speaking of that, you'll want to make sure to run at least a brigade +1 other detachment, or two brigades if you can, as CSM has some amazing strategems and you want to make sure you have the CP to use them.
One other thing I'd consider, is using the terminator lord, as a terminator sorcerer with warp time, so you can Deepstrike the terminators and the sorcerer, cast warp time on the terminators in order to guarentee a charge the turn they come in. You can then case Death Hex on whatever you want to charge, to make sure it has no Inv. Save. Death Hex will also be invaluble for fighting hive tyrants, as their 4++ save will stop half the lascannon shots going into them each turn otherwise.
These are some ideas.
As it stands, your list will do solid work in most pick up games. You'll have some hard counters, and you'll struggle at objective games. But, at tourniment play, you'll probably be in the upper middle half of the players (depending on the size and competititivness of the crowd). You'll live or die based on the predators and Fire Raptor, as the rest of the list won't hold without them.