I don't know if this would be of much help, but just approach the 18 marker as if it was a 21 marker. My teacher taught me that -
First highlight the keyword of the question and explain what it means before doing anything, so that it shows the examiner you're secure about understanding the meaning of the topic
second, look at the argument and key point that, to show that you are aware that the main argument will have a critique. For example- Functionalist see religion as promoting consensus and harmony rather than conflict. Highlight the **** out of the conflict and say " however... marxists/ feminists.."
then beginning outlining functionalism- durkheim, malinowski, parson, and if you have time, put an alternate view of functionalism= neo functionalist- britishness a civil religion?
Criticisms of functionalism? - religion is often dysfunctional= creates war, conflict.
= introduce your counter argument
critique your argument with other THEORIES/APPROACHES
= marxist= religion= false harmony, ideology, suppress the working class to conform
=feminism=religion= ideology used by the patriarchal society/ men, to suppress women into a subordinate position, gives women impression that they are equal to men however they are merely the second sex/ keep women into traditional roles etc. Evaluate the marxist/feminist theories
Critique the whole argument with postmodernism= religion and science are merely metanarratives= people disenchanted/ disillusioned. Because of the damage science and religion has caused= genetic mod, conflict, green harms, globalisation of crime, weapons of mass destruction etc. Feyerbend and Kaplan Science is a myth.
I kinda summed up a performa of what a 33marker would look like, but otherwise, if it was a 18marker, use only one theory to critique your argument.
Hope this was helpful