Does it take a long time to forgive someone?

The length of time will vary depending on how experienced a person is with the practice of forgiveness, how deeply the person was hurt, who hurt the person, whether or not the  other person is still being hurtful, and whether or not the other has apologized and seems sincere in that. Even if you are faced with the situation in which you have not practiced forgiveness much, you are deeply hurt, by someone who is supposed to love you, with on-going injustice and no apology, it still is possible to forgive.  It may take six months; it may take a year.  Yet, you likely will sense the progress being made (reduced anger, a confidence in the process, as examples).  So, do not think about forgiveness as “all or nothing.”  In other words, you will not need a year before you start to feel some psychological relief.  The positive changes can be rewarding and increase your motivation to keep on the forgiveness path.

Is it wrong to get angry with God when reacting to other people’s injustice? I feel that such a reaction is natural.

Even though it may seem natural to you, your getting angry with God (over injustices which you experience from people) is not good theology.  If God is all holy and sinless, then your forgiving God implies wrongdoing.  I prefer keeping a sound theology and understanding that God allows for the free-will actions of people, even if those actions are unjust.  People are the ones who behave badly, not God.  Rather than forgiving God, I suggest that you try to practice acceptance of what is allowed and then to forgive persons.  In this way, you do not diminish the attributes of God.

Might pride block forgiving? In other words, pride might lead a person to stand firm and say to the self, “I never will forgive unless the other apologizes!”

Yes, I do think that at times pride can lead to such a statement.  We have to be careful, however, because some cultures and faiths require an apology prior to forgiving.  If pride is blocking the forgiveness process, it might help if the person requiring the apology contemplates this question: “Are you hurting yourself by insisting on the apology?  Might you be preventing yourself from reducing resentment and being set free from emotional disruption as you wait for a prior response from the other?”

I can sympathize with my sister who hurt me, but I have a hard time empathizing with her (stepping inside her shoes, so to speak, and feeling what it is like being her). Can I ever feel compassion for her without empathy?

Not being able to empathize with your sister today does not mean you will never be able to do this.  Empathy can open the door to compassion.  Sympathy, or feeling sorry for her, also may be such a door to the eventual development of compassion.  Yet, as you are seeing, empathy is the deeper, more challenging perspective.  Here are some questions that might help you with empathy toward your sister:  Was your sister hurt by others some time in the past?  How deeply was she hurt?  Is she still carrying those wounds?  Can you see your sister’s struggles in life?  Your answers may induce a greater empathy for her as you see her wounds from her perspective.

In my experience, the longer a person harbors deep anger, then the longer pain and even a sense of hopelessness seem to rule their lives. As a person practices compassion in the face of others’ pain, the greater the likelihood that you are setting yourself and even your family free from pain (that started within you). So, I think it is really important to conquer that pain through forgiveness not only for yourself but also for loved ones. What do you think about this?

I agree with you and have nothing more to add to your wisdom.  All that you say makes sense to me.

I see a lot of anger being expressed in social media. What can you suggest as a way to start reducing this?

If more students have forgiveness education when they are young, then this will give them a chance to more deeply see the inherent (built-in) worth of others.  As we see that all people are special, unique, and irreplaceable, I truly think that deliberately hurtful verbal attacks on others will lessen.

I have a friend who uses sarcasm a lot. He ends up hurting people and then says, “Oh, come on! I was only kidding.” I suspect hidden and deep anger in him. What do you think?

If this is a pattern and if he sees that others are hurt (which you imply that he does), then, yes, I suspect the same: hidden (from him) and deep anger.  He may need to courageously explore who has hurt him in the past and try to practice forgiving, if he chooses.  It might lessen or even eliminate his hurtful sarcasm.