The answer to that question depends on how one defines "religion" As some define it, Lutheran, Baptist, Anglican and Catholic are not religions, they are all denominations which subsist within the larger Christian religion. Using this definition, the religion most similar to Catholicism would be Judaism followed by Islam. Each are religions "of the book" and accept the God of Abraham, Isaac and Moses as the one true God.
However, most will define the various denominations of Christianity as separate religions. In this context the closest religion to Catholicism within western Christianity would be Anglicanism (usually called Episcopalian out side of the UK) and Lutheranism. Each has a high church tradition which liturgically at least resembles Catholicism quite closely. They also have to a greater or lesser degree a sacramental theology which is central to Catholicism.
To get the closest to Catholicism, one has to look to the east and the various Orthodox Churches of Eastern Europe and Western Asia. These churches most notably the Greek Orthodox Church are the closest theologically and sacramentally. Their liturgies are very different, but the theology behind them are quite close. The major point of contention between the two (the filioque clause not withstanding) seems to be the Primacy of the Pope. In fact, there are within the Catholic Church several so called eastern rites which look nearly identical to the Orthodox liturgically but who have accepted the Pope as their head.
After the Catholic Church was founded in 325 (Council of Nicea), the Greek and Russian Orthodox churches historically branched out from the Catholic church, as also did the Protestant groups after the reformation. Nevertheless, most of the believes and principles of The Catholic Church prevailed. Trinity (=Jesus is God himself), life after death, hellfire, heavenly hope for all the faithful, secularization (participation in social and political matters), separation of clerus (clergy) from legus (the commoners) etc. So basically, all the divisions (sects -latin, meaning to divide or to part) of Christendom are similar although they themselves may feel they are different from each other.
It depends what you mean by Catholic Christianity. If you mean Latin Catholicism (ie the Western Church), the most similar would probably be High Anglicanism. They think very similar things and use the liturgical books of the Latin Church (IE the Roman Missal).
The various Orthodox Churches are also very similar to the Catholic Christian Church - they have 7 sacraments and have an almost identical understanding on most things, though they express them in different ways. There are however a number of Eastern Catholic Churches (such as the Maronite, Melkite, Ruthenian, etc) who are in full union with the Latin Church, but do not resemble them any more than the Orthodox.
Unity is more important than uniformity. Churches can resemble Catholicism and not be Catholic, but what is more important is being Catholic.
The great prophets Thomas White and Louis Wrigley discovered that Judism shares many features with the Roman Catholic religion.
Roman Catholicism is a form of the Christian religion, so other forms of Christianity bear a resemblance.
In a sense closer to the actual practice of religion, Churches in the Anglican Communion are very similar to Catholicism. The Episcopal Church is for the most part the US segment of the Anglican Communion. Other churches similar in practice are the Greek Orthodox and the Russian Orthodox churches. All of these churches have religious practices that emphasize ritual and sacramental religion. There are others. The Melchite Rite is a church that is in the Roman Communion, that is, it is part of the Roman Catholic Church, but with liturgy and practice very close to the orthodox churches.
The closest would be the Orthodox Church as they share over 99 percent of Catholic theology. There are a few differences that are currently preventing the two churches from again uniting. That would be followed by the Anglican and Lutheran Churches who are similar but separated by some major differences. However, many Anglicans are now forsaking their Church today and returning to Catholicism looking for the spiritual stability that is lacking today in the Anglican Church.
Any other Christian is closer to Catholic than any non-Christian.
The closest church to Catholicism, within the Christian religion, would be either the Anglican, the Lutheran, or the Orthodox, depending on which aspects you consider.
Episcopalian is most similar to Catholicism; its exception being disregard for the papacy.
South America is heavily dominated by the Roman Catholic faith. Nearly 80% of the population align with Catholicism. There are pockets of Protestants, Hindu, Islam, and other native religions.
The predominant religion is Roman Catholic. Although the Constitution states that there is freedom of religion, Catholicism is the only religion taught in public schools. Other religions in Peru are the Latter Day Saints (480,000 members), Buddhism (50,000), Bahá (41,000), and Islam (5,000)
Roman Catholicism (64.6%) Protestantism (22.2%) Non religious (8%) Other religions (5.2%)
Roman catholicism 64.6% Protestantism 22.2% Non religious 8% Other religions 5.2%
Religions: Roman Catholicism 60%, Protestantism 30%, other 10%Source: wikipedia
santeria
There are many religions in Oaxaca, the most common probably being Roman Catholicism. There are also groups of Protestants, Mormons, Jehovah's Witnesses, and other Indigenous religious groups
Officially Christian. Mostly Protestant and Catholic (certain regions lean certain ways). Switzerland is tolerant and has many other religions practicing here too.
No, Jesus was born a Jew and died as a Jew. However, he founded a "reformed" Jewish religion, or New Covenant, that came to be known as Christianity and Catholicism was the original and first Christian religion. All other Christian religions have their roots in Catholicism.
The two established religions in the 16th Century (the 1500s) were Buddhism, Hinduism, Judaism, Islam, Christianity in the forms of Roman Catholicism, Eastern Catholicism, Lutheran, Anglican and other Protestantisms, Daoism, and one or more others that I'm inadvertently leaving out.
The primary and official religion of Costa Rica is Roman Catholicism although many other religions have adherents among the population and religious freedom is guaranteed in the constitution.
French people follow the Christian, Jewish, Muslim, Buddhist, and other faiths. Some French also are unaffiliated.