Regarding the wording of the above statement of theme, the expression of this is better made in third person, rather than second.  Since theme itself is a universal idea, writing in the objective third person complements this objectivity. 

Also, in academic writing in which the student explicates a work of literature, using the third person is requisite.  This use of third person not only creates objectivity, but it lends verity to what the student writes since it eliminates mere opinion from the writing, and is thus more convincing.

Wording, too, is very important, as is sentence construction. With this in mind, another phrase should be used to replace the cliche, "what life throws at you."  (Always avoid cliches)  Here is a suggestion:

Perseverance in one's faith despite seemingly insurmountable obstacles as the key to survival, _____, and______ is the theme of Elie Wiesel's Night.  

The blanks have been placed as indications that three opinion are necessary if the student writes a five-paragraph essay since these three points form the topic sentences of the body paragraph.

For more help on writing an essay see the link below.

Taking what you can from the first two answers (both good, by the way) I would tell you what I tell all of my students.  When writing a theme statement, I do not allow my students to write statements that sound like advice.  Your statement, "Always have faith..." even with out saying "you" or "should," is giving direct advice.

Instead, take the same idea and attach either causes or effects of the main subjects, faith and adversity

Perhaps re-examine the idea of faith and adversity from Wiesel's perspective:
- does adversity cause faith to grow or weaken? - brainstorm a list of examples from the book then draw a common conclusion about what these examples are saying.
-  effects of having faith through adverse circumstances?  - again, make a list of textual examples, then from that list create a unifying statement.

You obviously know that theme statements themselves do not directly contain plot details.  However, remember that you PROVE your theme with the plot, so to me, specific examples are a logical place to start.

The thesis can be cleaned up a bit.  Prior to engaging in this, I would be interested to assess where you find evidence of this in the memoir.  One of the most striking elements of Wiesel's work, in my mind, is how he raises complexity in the belief of religion.  In reading his own thoughts about God and spirituality, I sense someone whose horrific nature of experience has lost the faith and belief to which you allude.  It seems to me that there is much more present about how one can feel abandoned by God, experience the indifference of divinity than redeemed by it.

Having said this, I think that the thesis can be tightened a bit.  How about, "Regardless of obstacles and challenges, Wiesel's work suggests that one should always hold religious faith dear"?  Another potential rewording would be, "Wiesel's book suggests that religious faith is needed to navigate the obstacles present in life." I frankly like to steer from the whole "you" in a formal writing and certainly in a thesis.

This is just my opinion, but I really like that statement and I would say that you should not change it at all.  However, that may be my personal preference and your own teacher might not agree.

Personally, I prefer it when my students say things in words that sound like them.  I do not like it when students sound like they are trying too hard to be formal.  A less formal tone makes it sound like a student really understands what she is saying and really believes it.

I mean, you could say "the theme of this novel is that it is important for a person to maintain faith in God, even in the face of adversity."  Sure, it sounds fancier, but I'm not sure it is better.

The same would go for the statement, "the theme of this work is that one must face up to any obstacles and try to overcome them by continuing to believe in God."