Answer
The Baha'i faith is one of the newer world religions stemming originally from Shi'ite Islam in Persia (modern-day Iran). However, it has come to achieve a unique status of its own. The Baha'i faith has distinguished itself as a unique world religion because of its size (5 million members), its global scale (236 countries), its practical autonomy from its parent religion of Islam (there is little blurriness between the two), and for its doctrinal uniqueness, being monotheistic yet inclusive.
The Baha'i faith’s earliest forerunner was Sayid Ali Muhammad who on May 23, 1844, declared himself the Bab ("Gate"), the eighth manifestation of God and first since Muhammad. Implicit to that statement was the denial of Muhammad as the last and greatest prophet and a denial together of the unique authority of the Koran. Islam did not take kindly to such thoughts. The Bab and his followers, called Babis, saw heavy persecution and were part of great bloodshed before the Bab was executed as a political prisoner just six years later in Tabríz, Ádhirbáyján, July 9, 1850. But before he died, the Bab spoke of a coming prophet, referred to as "He whom God will Manifest." On April 22, 1863, Mirza Husayn Ali, one of his followers, declared himself the fulfillment of that prophecy and the latest manifestation of God. He donned the title Baha'u'llah ("glory of God"). The Bab was therefore viewed as a "John the Baptist"-type of forerunner leading up to Baha'u'llah who is the more significant manifestation for this age. His followers are called Baha’is. The uniqueness of this budding Baha'i faith, as it has come to be called, becomes clear in the Baha'u'llah’s declarations. Not only did he claim to be the latest prophet foreseen in Shi'ite Islam, and not only did he claim to be a manifestation of God, but he claimed to be the second coming of Christ, the promised Holy Spirit, the Day of God, the Maiytrea (from Buddhism), and the Krishna (from Hinduism). A kind of inclusivism is apparent from the early stages of the Baha'i faith.
No other manifestation is said to have come since Baha'u'llah, but his leadership was passed on by appointment. He designated a successor in his son Abbas Effendi (later, Abdu'l-Baha "slave of Baha"). While the successors could not speak inspired scripture from God, they could interpret scripture infallibly and were viewed as the maintenance of God’s true word on earth. Abdu'l-Baha would appoint his grandson Shoghi Effendi as successor. Shoghi Effendi, however, died before appointing a successor. The gap was filled by an ingeniously organized governing institution called the Universal House of Justice which remains in power today as the governing body for the Baha'i World Faith. Today, the Baha'i faith exists as a world religion with yearly international conferences convening at the Universal House of Justice in Haifa, Israel.
The core doctrines of the Baha'i faith can be attractive in their simplicity:
1) Adoration of one God and the reconciliation of all major religions.
2) Appreciation of the diversity and morality of the human family and the elimination of all prejudice.
3) The establishment of world peace, equality of women and men, and universal education.
4) Cooperation between Science and Religion in the individual’s search for truth.
To these may be added certain implicit beliefs and practices:
5) A Universal Auxillary Language.
6) Universal Weights and Measures.
7) God who is himself unknowable nevertheless reveals himself through manifestations.
8) These manifestations are a kind of progressive revelation.
9) No proselytizing (aggressive witnessing).
10) The study of different Scriptures besides simply Baha'i books.
11) Prayer and worship is obligatory and much of that according to specific instructions.
The Baha'i faith is quite sophisticated, and many of its followers today are educated, eloquent, eclectic, politically liberal, yet socially conservative (i.e., anti-abortion, pro-traditional family, etc.). Moreover, Baha’is are not only expected to understand their own uniquely Baha'i scriptures, but are also expected to study the scriptures of other world religions. Therefore, it is quite possible to encounter a Baha'i who is more educated on Christianity than is the average Christian. Furthermore, the Baha'i faith has a strong emphasis on education combined with certain liberal values such as gender egalitarianism, universal education, and harmony between science and religion.
Nonetheless, the Baha'i faith has many theological gaps and doctrinal inconsistencies. Compared to Christianity, its core teachings are only superficial in their commonality. The differences are deep and fundamental. The Baha'i faith is ornate, and a full critique would be encyclopedic. So, only a few observations are made below.
The Baha'i faith teaches that God is unknowable in His essence. Baha’is have the difficulty of explaining how they can have an elaborate theology about God yet assert that God is "unknowable." And it does not help to say that prophets and manifestations inform mankind about God because, if God is "unknowable," then humanity has no reference point whereby to tell which teacher is telling the truth. Christianity rightly teaches that God can be known, as is naturally known even by non-believers, though they may not have a relational knowledge of God. Romans 1:20 says, "For since the creation of the world, His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead…" God is knowable, not only through the creation, but through His Word and the presence of the Holy Spirit, who leads and guides us and bears witness that we are His children (Romans 8:14-16). Not only can we know Him, but we can know Him intimately as our "Abba, Father" (Galatians 4:6). True, God may not fit His infinity into our finite minds, but man can still have partial knowledge of God which is entirely true and relationally meaningful.
About Jesus, the Baha'i faith teaches that He was a manifestation of God but not an incarnation. The difference sounds slight but is actually enormous. Baha’is believe God is unknowable; therefore, God cannot incarnate Himself to be present among men. If Jesus is God in the most literal sense, and Jesus is knowable, then God is knowable, and that Baha'i doctrine is exploded. So, Baha’is teach that Jesus was a reflection of God. Just as a person can look at a reflection of the sun in a mirror and say, "There is the sun," so one can look at Jesus and say, "There is God," meaning "There is a reflection of God." Here again the problem of teaching that God is "unknowable" surfaces since there would be no way to distinguish between true and false manifestations or prophets. The Christian, however, can argue that Christ has set Himself apart from all other manifestations and has confirmed His self-attested divinity by physically rising from the dead (1 Corinthians 15), a point which Baha’is also deny. While the resurrection would be a miracle, it is nonetheless a historically defensible fact, given the body of evidence. Dr. Gary Habermas, Dr. William Lane Craig, and N.T. Wright have done well in defending the historicity of the resurrection of Jesus Christ.
The Baha'i faith also denies the sole sufficiency of Christ and of Scripture. Krishna, Buddha, Jesus, Muhammad, the Bab, and Baha'u'llah were all manifestations of God, and the latest of these would have the highest authority since he’d have the most complete revelation of God, according to the idea of progressive revelation. Here, Christian apologetics can be employed to demonstrate the uniqueness of Christianity’s claims and its doctrinal and practical truthfulness exclusive of contrary religious systems. The Baha'i, however, is concerned for showing that all the world’s major religions are ultimately reconcilable. Any differences would be explained away as:
1) Social Laws—Instead of supra-cultural Spiritual Laws.
2) Early revelation—As opposed to the more "complete" later revelation.
3) Corrupted Teaching or Misinterpretation.
But even granting these qualifications, the world’s religions are too varied and too fundamentally different to be reconciled. Given that the world’s religions obviously teach and practice contrary things, the burden is on the Baha'i to salvage the world’s major religions while dismantling almost everything foundational to those religions. Ironically, the religions which are most inclusive—Buddhism and Hinduism—are classically atheistic and pantheistic (respectively), and neither atheism nor pantheism is allowed within the strictly monotheistic Baha'i faith. Meanwhile, the religions that are least theologically inclusive of the Baha'i faith—Islam, Christianity, Orthodox Judaism—are monotheistic, as Baha'i is.
Also, the Baha'i faith teaches a sort of works-based salvation. The Baha'i faith is not much different from Islam in its core teachings about how to be saved except that, for the Baha'i, little is said about the afterlife. This earthly life is to be filled with good works counterbalancing one’s evil deeds and showing one’s self deserving of ultimate deliverance. Sin is not paid for or dissolved; rather, it is excused by a presumably benevolent God. Man does not have a significant relationship with God. In fact, Baha’is teach that there is no personality in God’s essence, but only in His manifestations. Thus, God does not submit easily to a relationship with man. Accordingly, the Christian doctrine of grace is reinterpreted so that "grace" means "God’s kind allowance for man to have the opportunity to earn deliverance." Built into this doctrine is a denial of Christ’s sacrificial atonement and a minimization of sin.
The Christian view of salvation is very different. Sin is understood as being of eternal and infinite consequence since it is a universal crime against an infinitely perfect God (Romans 3:10, 23). Likewise, sin is so great that it deserves a life (blood) sacrifice and incurs eternal punishment in the afterlife. But Christ pays the price that all owe, dying as an innocent sacrifice for a guilty humanity. Because man cannot do anything to unblemish himself or to deserve eternal reward, he either must die for his own sins or believe that Christ graciously died in his place (Isaiah 53; Romans 5:8). Thus, salvation is either by God’s grace through man’s faith or there is no eternal salvation.
It is no surprise then that Baha'i faith proclaims Baha'u'llah to be the second coming of Christ. Jesus Himself warned us in the Gospel of Matthew concerning the end times: "Then if any one says to you, 'Lo, here is the Christ!' or 'There he is!' do not believe it. For false Christs and false prophets will arise and show great signs and wonders, so as to lead astray, if possible, even the elect" (Matthew 24:23-24). Interestingly, Baha’is typically deny or minimize any miracles of Baha'u'llah. His unique spiritual claims are based on self-attested authority, uncanny and uneducated wisdom, prolific writing, pure living, majority consensus, and other subjective tests. The more objective tests such as prophetic fulfillment employ heavily allegorical interpretations of Scripture (see Thief in the Night by William Sears). The belief in Baha'u'llah largely reduces to a point of faith—is one willing to accept him as the manifestation of God, in the absence of objective evidence? Of course, Christianity also calls for faith, but the Christian has strong and demonstrable evidence along with that faith.
The Baha'i faith therefore does not accord with classical Christianity, and it has much to answer for in its own right. How an unknowable God could elicit such an elaborate theology and justify a new world religion is a mystery. The Baha’i faith is weak in addressing sin, treating it as if it were not a big problem and is surmountable by human effort. Christ’s divinity is denied, as is the evidential value and literal nature of Christ’s resurrection. And for the Baha'i faith, one of its biggest problems is its pluralism. That is, how can one reconcile such divergent religious without leaving them theologically gutted? It is easy to argue that the world’s religions have commonalities in their ethical teachings and have some concept of ultimate reality. But it is another beast entirely to try to argue unity in their fundamental teachings about what the ultimate reality is and about how those ethics are grounded.