While writing a critical appreciation, we critically evaluate the piece. The first thing to do is its in-depth analysis. In case of poetry, we should look for things like rhyme scheme, rhythm, or structure. Next, we should check if there are any literary devices, such as figurative language, parallelism, imagery, symbolism, etc. Once we can completely understand the poem, along with the theme and devices used to convey the meaning, we can proceed to take a more critical stand and evaluate its effectiveness.
This (I believe) poem's structure is quite unique and it resembles Japanese Haiku a little bit. Haiku comes from old Japanese literature and its structure is - three verses with 5, 7 and 5 syllabels respectively. The poem "I Believe" is made up of 6 stanzas, 3 lines each, similarly to Haiku. What is important to remember is that Haiku was usually created in order to show the relation between a person and the nature. To grasp an extremely fleeting moment and freeze it in time. Knowing that, we could try to extrapolate and compare the poem's contents with nature-centered theme which was common for Haiku. It might also be interesting to ask yourself whether it shows any kind of connection to God.
In the poem we can find an anaphora - a retorical device used to put more emphasis on a particular part of the text by repeating a certain phrase. In this case it is the phrase I believe which can be used literally - showing the strong belief of the subject or it might be used ironically, to convey the opposite meaning instead. Anaphoras are found abundantly in Bible which leads to a conclusion that the author might have wanted to strenghen the religious them of the poem even more.