Most of the people would afraid to come to the funerals. There would be many stories that would be heard by them about the people who die suddenly. Many people strongly believe that such people would not leave this world and would be roaming around as ghosts on this Earth. Since, they would be afraid to come to the funeral which is arranged by you. Since it is the religious belief you could not deny it but to make such people attend the funeral and bless the soul you could choose the traditional cross printed invitations. This way it becomes easy for you to get rid of the fears of such coward people who would try to give several other reasons for not attending the gathering.
Of course, traditional cross is so sacred and one would not simply use a plus sign in italic style to make look like a cross. At the same time you could not self-design the cross as it would be too typical and too time taking. So, try to pick the funeral pamphlets that of traditional cross category. You could decide the size of the cross depending on the content that you want to add in the invitation. Apart from just targeting to make the guests attend the gathering you could also ensure that the cross brings in some holy atmosphere wherein everyone attending the gathering would pray for the peaceful rest of the soul.
So, hope you now have a valid reason as to why you should choose the traditional cross templates that are very easy to print at home and then give it in the hands of the guests whom you wish to make their presence in the gathering. Before you blindly say no, you at least look at the templates that are decent in their design.