Here is a superb answer from Rabbi Tovia Singer’s website. I know it is long, but I recommend reading the whole thing. Enjoy! (from note that Rabbi Singer is not affiliated with this site in any way, and all credit for this post goes to him)

Because your letter touches on an intangible condition rooted in the heart of the believer, I am certain that many visitors to our website will not fully grasp the importance of your main question.  It would not be an overstatement to say that your thoughtful letter contains one of the most important questions that could be asked of me.

Ever since I began working to help Jews return to Judaism, I have received numerous letters and listened to many stories from people like yourself filled with personal anecdotes recounting how their lives were miraculously changed as a result of their newfound faith.  Many of the accounts of these new believers described how their drug addiction and alcoholism inexplicably ceased.  Recently, I received a letter from a middle-aged Jewish woman who maintained that as a result of her conversion to Mormonism, her festering illnesses were miraculously cured.  Following a recent lecture, a young man vividly recalled how his plaguing depression had lifted soon after he converted to the Catholic Church.  For him, the euphoria that had now replaced his nagging bouts of depression bore testimony to the validity of the teachings of Roman Catholicism.

While I was speaking in Southern California a number of years ago, I met four young men who were members of Hare Krishna.  It wasn’t a planned meeting, we just happened to strike up a conversation as we were crossing the same busy street in Los Angeles.  To my utter shock, three of these lost souls were Jews.  As I listened attentively to the testimonials of these oddly dressed fellows, each of them carefully described how their newfound religion had transformed their lives.  They joyfully spoke of their joining this eastern sect and I could sense the elation and inner peace they felt.  They were certain that what they believed was true and it was quite apparent that they were more spiritual now than they had ever been in their former lives.

When considered individually, such moving accounts seem quite impressive.  Once these remarkable testimonials are examined as part of a larger pattern, however, they present us with a serious theological problem.  Although each of these extraordinary stories may appear to the novice as evidence of the validity of their newly acquired faith, the fact remains that these variant religions cannot all be valid.  When it comes to spiritual experiences and miraculous occurrences, things get very messy.  The realm of faith would be very tidy if only one religion produced life-altering transformations and miraculous occurrences.  To the dismay of the fervid believer, however, this may be the most disorganized arena of organized religion.  In fact, the life-changing experience that you describe in your letter is a universal phenomenon produced by virtually all faiths, and people from just about every religion can claim “almost unbelievable change in the character and personality” of the people whom they touch, regardless of the truth of the doctrines they preach.  In essence, there is no relationship between spiritual transformation which occurs in the heart of the faithful believer and the spiritual truth which he espouses.

Bear in mind, our planet is brimming with world religions such as Hinduism, Buddhism, and Islam, each of which boast many hundreds of millions of adherents.  The multitudes of these devout believers in their diverse faiths all remarkably speak of the very same “character and personality” transformation which you describe within the context of your religion, Christianity.  Yet, as we pay careful attention to their personal testimonials which movingly recount how their religious faith has transformed them, it seems as if they all somehow belong to the same religion — their testimonials all breathe with the experience of a connection with the divine.

According to your doctrinal barometer, however, billions of these devoted faithful are lost souls merely following a “false religion.”  Realize, therefore, that their startling religious experiences cannot possibly speak of the validity of their theology.  For example, Hinduism and Islam have radically different teachings on the nature of God; yet, how is it that Hindus, Christians, Mormons, and Muslims are all at the very same time experiencing this profound religious conversion which you describe?  This question becomes particularly puzzling when we consider your implied assertion that spiritual transformation among the faithful will point us in the direction of spiritual truth.  All of these religions cannot possibly be transmitting truth; nevertheless, each of them does ignite profound spiritual changes within the character and personality of their devoted masses.

The question that naturally comes to mind is: Why would God allow all religions, regardless of the theological untruths they espouse, to ignite a spiritual passion within the heart of the believer?  The Bible contains a record of many individuals and nations who possessed fervent devotion to their idolatry.  Nonetheless, their spiritual adultery is condemned as an utter abomination, regardless of the spirituality and transformation they derived.  Why would the Almighty permit religions whose fundamental teachings have no basis in truth to produce life-transforming experiences and miraculous occurrences in the lives of their devout followers?

The answer is found in the beginning of Deuteronomy where the Torah addresses this dilemma in an even more startling scenario.  In Deuteronomy 13:1-2 the Bible raises the question of what to do when a “prophet” offers to show a miracle in order to lend credibility to his message.  How are we to respond if, in fact, the promised miracle comes to pass just as he predicted?  Should we then follow this “prophet” even if he encourages us to worship other gods which are unknown to our people?  “You must not listen to the words of that prophet or dreamer,” the Torah emphatically declares.  God did not send him.

The obvious question is: Why would the Almighty permit religions and prophets who teach unsavory doctrines to produce spiritual transformations and miraculous events?  The answer lies in the verses that follow.

The Lord your God is testing you to find out whether you love Him with all your heart and with all your soul.  It is the Lord your God you must follow, and Him you must revere.  Keep His commands and obey Him; serve Him and hold fast to Him. (Deuteronomy 13:3-4)

God is truly testing you with the experiences and observations you have had and made.  This is your choice in a world where free will hangs in its perfect balance.  Will you worship the God of Israel alone or turn to gods whom the nation of Israel has not known?  If we lived in a world where only one religion could produce spirituality and miraculous life-altering experiences, that precious balance of free will could not exist.

In the 18th chapter of I Kings, the Bible relates that when Elijah had challenged 450 priests of Baal to bring a sacrifice to their gods and see if their offering would be miraculously accepted with fire, there was a peculiar spectacle which followed.  It seemed as though there was no doubt in the minds of these pagan worshipers that Baal would hear their supplications and consume their bullock with a heavenly fire.  The Bible vividly recounts how they enthusiastically entreated Baal and prayed fervidly for a miracle all day.  They even climbed on top of the altar and began to prance beside their sacrifice, and when that failed to secure a response from their gods, in their frantic zeal they used knives and lancets to slice away flesh from their bodies.  These prophets of Baal were on fire for their gods.  Regardless of their unyielding zeal for their idols, they were commanded to turn away from these abominations.

In fact, the prophet Jeremiah warns us that the spirituality gained from following false prophets and corrupt teachers may become so encompassing and overwhelming that you may begin to have dreams regarding these prophets.  Jeremiah concludes,

. . . for thus says the Lord of hosts, the God of Israel, “Do not let your prophets and your diviners who are in your midst deceive you, nor listen to your dreams which you cause to be dreamed; for they prophesy falsely to you in My name.  I have not sent them, says the Lord.” (Jeremiah 28:8-9)

Jeremiah’s message is clear.  If the prophet’s message has so permeated your being to the point that you are having dreams of these false prophets and their false teachings, you alone are the one who is responsible for these improper apparitions.  God has not sent them.

Furthermore, at the very end of your question you insisted that “the God of all mankind would preempt a false religion in His name, which would lead millions from the true path, and towards damnation.”  This assertion is incorrect; for if your conclusion were accurate, why do these masses of spiritually blind believers make such deplorable choices about their religious affiliations?  Why hasn’t God in fact “preempted” these false religions?  Why is Islam the fastest growing religion in the world when your Christianity is supposedly the only life-transforming truth?  In essence, how could so many be so wrong about something so crucial as religion when, according to your reckoning, the Almighty would never “lead millions” away from His true path?

A careful reading of the Bible reveals that, in fact, God does not lead mankind away from His true path.  This was always man’s decision alone, and it will forever remain in his domain.  And your Creator never removed that decision from within your reach.  As the Torah declares in Deuteronomy 30:15-19,

See, I have set before you today life and good, death and evil, in that I command you today to love the Lord your God, to walk in His ways, and to keep His commandments, His statutes, and His judgments, that you may live and multiply; and the Lord your God will bless you in the land which you go to possess.  If, though, your heart turns away so that you do not hear, and are drawn away, and worship other gods and serve them, I announce to you today that you shall surely perish; you shall not prolong your days in the land which you cross over the Jordan to go in and possess.  I call heaven and earth as witnesses against you today, that I have set before you life and death, the blessing and the curse; therefore choose life, that both you and your descendants may live.

God permits man to become enraptured with false religions for the same reason He permits a married man to be attracted to women other than his wife.  Free will is within your grasp.  If this ordained tender balance of free will were ever compromised, virtue would remain beyond the reach of mankind.  Don’t, though, look to spirituality and miraculous life-changing events as your guide to truth in faith.  Look to the Bible alone for this eternal instruction.  Once you have committed your life to truth in the God of Israel, joyously take part in the spiritual food it provides.  Never permit spiritual expressions to become your barometer for truth.  Your foundation must be the Jewish scriptures.

Best wishes for a happy and healthy New Year.

Very sincerely yours,

Rabbi Tovia Singer