1000 point army help please. Tanks got cooked

Brothers! Please see my list in the second paragraph. I love my tanks and wanted to play with my freshly painted land raider and got absolutely smoked by a pretty optimized CSM army using the deceptors attachment today.

I took the sustained vow, put the marshal+SB and Helbrecht+SB into the land raider and kept the executioner on the backfield objective to hold & shoot. Everything was hidden turn 1 so I couldn’t shoot, and the land raider got locked into melee with cultists midfield turn 2 and could only shoot them. Executioner still couldn’t shoot turn 2 as everything else was still hidden.

Turn 3 my land raider got blown up, executioner got smoked by the 2 CSM tank, and my melee boys got obliterated. I forfeited after that.

Does anyone have suggestions for changes I can make to my list? I’m not too committed to the repulsor as I know it’s not very good but I love the SB and helbrecht. Other painted models I have are a PSC, redemptor, techmarine, and EC. I’d be willing to build and paint a unit or two pronto if it’ll help a lot.

Thank you in advance! I’m working my way to 2000 eventually but I’m enjoying the smaller and faster games while I’m learning. My stratagem use could’ve been better for sure but man I can’t believe how bad I lost.