The Large Distance Between Beliefs and Truth

People normally take their beliefs as truths, but we don't know  certainly  for certain  whether they are true or false. Therefore, the ramifications  of people’s  for people  realizing this could be very shocking. This leads to the possibility that beliefs could be either beneficial or harmful depending on how much we believe in them. People should know that their beliefs don't have all the answers, but it's not bad to have a belief, as long as we don't overestimate it.

 First of all, there  There  are some people who overestimated their beliefs and they had to pay the consequences. There was a case about a couple who were accused of killing their daughter, because she didn’t receive  a  proper medical treatment. These parents thought that praying for  her  their  daughter could be as effective as  a  conventional treatment given by a doctor. In fact, if the child had received medical treatment hours before her death, she might have lived. However, this was not possible because of  their  her  parents’ belief.

 Second of all, other  Other  people followed their beliefs, but they didn’t think this was the only answer. In  this  another  case, a man was diagnosed  with  a severe ailment, but he was determined to overcome this problem. At this point, he believed that if he had a positive attitude, he would live longer. Finally, having his medical treatment together with the positive attitude made him live longer than doctors expected, and this possibly couldn´t have happened if he hadn’t followed this belief.

In brief, having beliefs  could bring  can have  consequences. Whether they are good or bad just depends on us.  First,   Some  people could think their beliefs have all the answers and they don’t need anything else.  On the other hand, others  Others  know beliefs are not everything and trust in real facts.

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Your English is very good.  However, let me provide a couple of points.

If you start one paragraph with "First of all," the next paragraph would start with "Secondly" or "Second", not with "Second of all".

If you start one sentence with "On the other hand," the previous sentence should have started with "On the one hand", and not with "First".  (That is, "On the one hand, ..... On the other hand, .....")

Further, you should use "First" and "Second" only when introducing paragraphs that work towards proving the *same* point.  For example:

I like learning English.

First, it is the most common language in the world.

Second, many interesting books are available only in English.

You should not use "First" and "Second" when introducing paragraphs that work towards proving *different* points.  For example, the following is not correct.

I like learning English.

First, it is the most common language in the world.

Second, other people prefer learning Chinese.

This is why I struck out your use of "First of all" and "Second of all".  Both paragraphs concerned the same topic, but made very different points.