In most states, the answer would be less clear, as First Amendment protections begin falling away quickly when you enter private property.
In California, though, there is some strong precedent indicating that this behavior would be protected. In Robins v. Pruneyard Shopping Center, 23 Cal. 3d 902 (1979), the California Supreme Court held that "the soliciting at a shopping center of signatures for a petition to the government is an activity protected by the California Constitution."
That case adopted the reasoning of a dissent in a previous case where the court had rejected such an argument:
It bears repeated emphasis that we do not have under consideration the property or privacy rights of an individual homeowner or the proprietor of a modest retail establishment. As a result of advertising and the lure of a congenial environment, 25,000 persons are induced to congregate daily to take advantage of the numerous amenities offered by the [shopping center there]. A handful of additional orderly persons soliciting signatures and distributing handbills in connection therewith, under reasonable regulations adopted by defendant to assure that these activities do not interfere with normal business operations ... would not markedly dilute defendant's property rights.
I'd bet there is case law addressing religious leafleting, as well, but I don't know California law well enough to cite to it. Even if there isn't, though, the First Amendment's requirements of content-neutrality in government decisionmaking would probably require that the same protections be extended to religious speech.
Of course, the answer to these kinds of questions always depends on the specific facts, requiring you to engage a lawyer to get a reliable answer. For a lower cost, you could also just ask the local police if they would enforce a request from the property owner to have you removed.