California state law criminally restricts trespassing via Cal. Pen. 602.8(a):
Any person who without the written permission of the landowner, the
owner's agent, or the person in lawful possession of the land,
willfully enters any lands under cultivation or enclosed by fence,
belonging to, or occupied by, another, or who willfully enters upon
uncultivated or unenclosed lands where signs forbidding trespass are
displayed at intervals not less than three to the mile along all
exterior boundaries and at all roads and trails entering the lands, is
guilty of a public offense.
However, subdivision (c) states exceptions, that this does not apply to:
...(2) Any person on the premises who is engaging in activities
protected by the California or United States Constitution.
(There are other exceptions for process-servers, surveyors, and labor union activities). Additionally, anyone who remains on property after having been told to go away is guilty of trespass: simple entering when there is a no-trespassing sign is allowed in the case of religious or political canvassing. So at the state level, a division is made between protected activities (First Amendment issues) and non-protected ones (Commerce Clause issues), where criminal trespass is not applicable to religious or political solicitations.
Aliso Viejo limits canvassing thusly:
No person shall enter upon any residence or place of business and ring
the doorbell, or rap or knock upon any door, or create any sound in
any other manner calculated to attract the attention of any occupant
of such premises, for the purpose of securing an audience with the
occupant and engaging in peddling, solicitation or canvassing in
defiance of a notice described in subsection (C) of this section.
and subsection (c) says:
Notice by the owners or occupants of any residence or place of
business of their unwillingness to receive any uninvited peddlers,
solicitors, canvassers, or handbills shall be given by displaying a
weatherproof card, decal, or sign easily seen from the public
right-of-way or the normal entryway to a house or dwelling. The notice
must be placed upon or near the main entrance door to the residence or
place of business and must state: “No Solicitors,” or words to that
effect, with the letters at least one inch high.
Solicitors and peddlers, but not canvassers, are also required to have a license. By their definitions, solicitors request things of value, and peddlers engage in commerce: canvassers engage in First Amendment protected activities, including disseminating commercial information (but not making sales). Violation of the code is punished variably, basically at the discretion of the prosecutor (there being a choice between infraction and misdemeanor dispositions).
The Santa Monica police say that "There are many legitimate organizations that solicit door-to-door, either to sell products and services or to promote a religious, political or charitable cause. However, there are also a growing number of individuals who illegally solicit with the purpose of committing fraud.
So when someone knocks at your door, ask the person to produce the required license before he/she begins a sales pitch". The implication is that you have to have a license to engage in "canvassing", which is almost guaranteed to be incorrect (First Amendment thing).
The Santa Monica Code says in 6.32.040 that "Every person engaged in soliciting, canvassing, taking orders or peddling of goods, wares, merchandise or services shall pay a license fee in accordance with Section 6.12.010(a) of this Code" (that section however does not demand a fee for activities not generating money, i.e. political and religious disseminations).
Santa Monica also limits door to door operations via a signage ordinance:
No solicitation or peddling shall be conducted at any place of
residence in the City where any sign prohibiting trespassing or
solicitation has been posted or displayed. If the sign posted or
displayed limits the hours of trespassing or solicitation, no
solicitation or peddling shall be conducted at any place of residence
in the City during the time period posted or displayed
It is of interest that the signage ordinance does not mention canvassing (and canvassing is not defined), but the license law does. So in terms of legal prohibitions, it depends on municipality, and perhaps interpretation of local ordinances.
Of course, one can always put up a sign saying "No Religious Solicitations" and hope that persuades the person, and one can sue for damages, if there are arguably any damages. "Do Not Disturb" might be more effective.
SCOTUS noted in Martin v. City of Struthers that "Whether such visiting shall be permitted has in general been deemed to depend upon the will of the individual master of each household, and not upon the determination of the community" and ruled that Struthers may not "make this decision for all its inhabitants" (on First Amendment grounds).
Hynes v. Mayor of Oradell addressed a licensing requirement (struck down as overly vague and broad) that covered canvassing, and said
A municipality has the power to enforce reasonable door-to-door
soliciting and canvassing regulations to protect its citizens from
crime and undue annoyance. The Court has consistently recognized that
a narrowly drawn ordinance that does not vest in municipal officials
the undefined power to determine what residents will hear or see may
serve these interests consistent with the First Amendment
so a license requirement for religious canvassers could be consistent with the SCOTUS stance: if it is narrowly tailored. Subsequently, in Watchtower v. Stratton, the court stated (regarding a licensing requirement) that
§ 107 of the ordinance, which provides for the posting of "No
Solicitation" signs and which is not challenged in this case, coupled
with the resident's unquestioned right to refuse to engage in
conversation with unwelcome visitors, provides ample protection for
the unwilling listener
A "No Solicitation" sign then has the desired effect: it is legal to make it illegal to solicit in the presence of a No Soliciting sign. The specific ordinance was not narrowly tailored (to "preventing fraud"); requiring a surrender of anonymity. Other cases such as Ohio Citizen Action v. City of Englewood, 671 F.3d 564, Bd. of Trustees of State Univ. of New York v. Fox, 492 U.S. 469 have overturned anti-solicitation laws as not being narrowly tailored: for instance, solicitations too early in the morning or too late at night are constitutional; and in general, a sign by the owner means "keep out", and the first amendment does not overrule private property rights.
It is unlikely that any ordinance mandating "uniform business practices" would survive; the concept is too vague and unlimited, and would be a significant burden on any business. And, of course, religions have constitutional protections that businesses lack.