Can also be Eitqaad, Bharosa, Imaan

Just adding one more word to the synonyms already provided :-)

Faith --> Hindi --> Shruddha --> श्रद्धा, to believe in, usually on a religious plane.

I would use the Hindi word "vishwas" when there is an issue of "trust", but it is your context that would be the deciding factor.

Have faith in me, I shall deliver --> मुझमें विश्वास (vishwas) रखो, मैं काम करूँगा.

Have faith in God, He will show the light --> ईश्वर में श्रद्धा (shruddha)रखो, वह रास्ता दिखाएगा.

Hth,

Sanjay.

aqida;aiman;muzhab;bhrosaayaqeen;iqrar;zama dari etc[Ferozesons English to URDU Dictionary]
trust;system of religious beliefs[concise english...urdu dictionary]
firm and earnest belief;reliance;trust;confidence;creed;loyality;fidelity,vafa,yaqeen;
Ali has faith in his new friend.
faith [ fayth ] (plural faiths)

noun

1. belief or trust: belief in, devotion to, or trust in somebody or something, especially without logical proof


2. religion religion or religious group: a system of religious belief, or the group of people who adhere to it


3. religion trust in God: belief in and devotion to God
Her faith is unwavering.


4. set of beliefs: a strongly held set of beliefs or principles
people of different political faiths


5. loyalty: allegiance or loyalty to somebody or something


[13th century. Via Old French feid from Latin fides “trust, belief” (source of English confide and fealty). Ultimately from an Indo-European word that is also the ancestor of English federal.]


keep faith with somebody or something to be loyal or true to a person or promise


on faith without demanding proof





--------------------------------------------------
Note added at 1 hr 2 mins (2004-10-27 22:48:44 GMT)
--------------------------------------------------

biswas (p. 0156)

H bisvAs biswas [S. vizrvAmn], s.m. Trust, confidence, faith, belief, reliance, dependence: -- biswas rakhna, biswas karna (-ka; or -par), To put trust (in), to confide (in), rely (on), to trust, believe, credit: -- biswasghat, s.f. Destruction of confidence, breach of faith, violation of trust, treachery, treacherous friendship;-<-> biswas-ghati, s.m. One who betrays confidence, traitor, treacherous friend.



--------------------------------------------------
Note added at 1 hr 4 mins (2004-10-27 22:50:56 GMT)
--------------------------------------------------

yaqin (p. 1250)

A yaqin (v.n. of the measure fa`il, fr. `to know for certain\'), s.m. Certain of sure knowledge, certainty, assurance, confidence, conviction, belief, opinion; truth, true faith, infallibility, evidence; -- adj. Certain, sure, positive, true; -- adv. For certain, with certainty, truly: -- yaqin ana (-ko), The certainty or assurance to possess (one), to be or become assured (of, -ka), to believe:-<-> yaqin janna, v.t. To know for certain, to be assured or positive (of): -- yaqin dilana, or yaqin karana (-ko), To cause (one) to believe; to assure: -- yaqin karna, v.t. To ascertain; to believe: -- yaqin lana (-par), To pin (one\'s) faith (to), to believe, to credit: -- yaqin manna, v.t. To regard as certain or true, to be assured of; to believe:-<-> yaqin mano, or yaqin-karo, or yaqin jano, Be assured; believe (me): -- yaqin na karna, v.t. Not to believe; to mistrust: -- yaqin-e-wasiq, s.m. Strong belief or conviction


--------------------------------------------------
Note added at 4 hrs 36 mins (2004-10-28 02:22:19 GMT)
--------------------------------------------------

Above Notes are from A Dictionary of Urdu,Classical Hindi & English.

Depending on the context the word can be differently translated.
Say, if want to express that you have faith in some person, you should use the word VISHWAS. For example "Mera uss vyakti mein vishwas hai" i.e. Í have belief in that person'.
BHAROSA is a very commonly used hindi word. If you have faith in somebody thinking that the latter will come forward with help, etc, in case of need, you may straightaway say that 'Mein usspar bharosa karta hun".
AASTHA is a word in Hindi used with respect to religion, religious beliefs, God. If you want to say that you belief in Christianity, you can express "Meri Isaai dharm mein aastha hai". You can also say "Mara Isaai dharm mein vishwas hai", but when we use the word AASTHA it further explains that we are talking about religion and pious feelings related with religion and religius beliefs. I do not think that you can straight away find some book explaining very fine aspects of word usage in Hindi. However as an Indian with Hindi as my mother tongue and some experience of translation, I can further say that when you use the word VISHWAS in connection with religion as above, it is too straight forward expression of your feelings. It gives a feeling that you have faith in Christianity and don't believe in other religions. However, when you use the word AASTHA, it becomes a very respectful expression appropriate for religious thoughts and feelings. It just gives an expression that you have chosen Christianity as your path for realisation of God.
I hope I have been of some help to you by the above explanation. If you can not follow the above transcription of the Hindi sentences and want them in Hindi Devnagri script, kindly let me know. If you send the complete English sentence, you are translating, I will probably be able to exactly translate and help you.