I don't think it is. Suppose a buddhist, a muslim a Christian and a Jew all took religious icons to market to sell, and three were permitted to sell theirs but the muslim was refused permission. That is plainly discriminatory, if the reason for permission being refused is his religion (rather than some other justifiable reason, e.g. not having a licence or similar).
But suppose none of them were allowed to sell your icons on the basis that the market is fruit and veg only. That cannot be discrimination. The fact that the product is religious in nature does not mean that anybody is being discriminated against on the grounds of his religion: he is not. However the service they all require is not one that the service provider offers. To put it another way, they can pick and choose what services they provide, but they cannot pick and choose who they provide those services to on the basis of the protected characteristics identified by the Act.