Mormons, the Jewish religion, and various others follow some sort of creed, either written or not, which tells them that no everyone is welcome to just join their faith or attended their services. I know that most Jewish temples probably wouldn't stop you at the door. I know that to join the LDS church isn't impossible if you really want to. But, Mormons don't just let people enter their temple. You have to practically be a card carrying member of the LDS church and Jews don't just let you decide to be a Jew. There is a process of elimination for people who want to convert and not just as easy as saying I am ready. The point is, some religions and denominations of those religions seem to put a stone between us and God. I was always under the impression God made us all and his house is open to all who seek to enter and his mercy is given to all who seek it. Am I wrong? If so, why?
Mormon's,

That is what I meant. Card carrying to go to temple. But, since when and where did God mention that he wanted any religion to issue a card to enter an exclusive club (temple) to worship him? Point to an OT or Torah verse.