Kindness In Islam.

These words from the Quran and hadith shows well how Kindness is very highly regarded in Islam.

"Invite to the way of your Lord with wisdom and beautiful preaching; and argue with them in ways that are best and most gracious; for your Lord knows best who have strayed from His Path, and who are truly guided."
Quran 16:125

"Do you know what is better than charity and fasting and prayer? It is keeping peace and good relations between people, as quarrels and bad feelings destroy mankind."
(Muslims & Bukhari)

"Reviling a Muslim is disobedience to God, and fighting with him is infidelity."
(Bukhari, Muslim)

"Narrated Anas ibn Malik: The Prophet (peace_be_upon_him) said: Three things are the roots of faith: to refrain from (killing) a person who utters, "There is no god but Allah" and not to declare him unbeliever whatever sin he commits, and not to excommunicate him from Islam for his any action."
(Abu-Dawud)

"The most excellent Jihad is that for the conquest of self."
(Bukhari)

"Kindness is a mark of faith, and whoever is not kind has no faith." (Muslim)

"Whoever is kind, Allah will be kind to him; therefore be kind to man on the earth. He who is in heaven will show mercy on you."
(Abu Dawud and Tirmidhi)

"You will not enter paradise until you have faith; and you will not complete your faith till you love one another."
(Muslim)

"You have two characters which God likes; gentleness and deliberation."
(Muslim).

"By Him in whose hand my soul is, you will not enter paradise unless you believe, and you will not truly believe unless you love each other."
(Bukhari and Muslim)

"…Try to pass your mornings and evenings in a state where your heart is free from all ill-feelings, jealousy and hatred for everyone, and remember that this is my Sunnah, and he who loves my Sunnah will be with me in paradise."
(Tirmidhi)

"Those in whose hearts is no mercy for others will not attain the mercy of Allah."
(Bukhari and Muslim)

"Verily, Allah is mild and is fond of mildness, and He gives to
the mild what He does not give to the harsh."
(Muslim)

"One who lacks kindness of heart lacks all good."
(Muslim)

"Allah is gentle and loves gentleness in all things."
(Bukhari and Muslim)

Islam is the religion of kindness. This does not contradict your right to feel angry when Muslims are oppressed, poor, suffering and have a lot of injustices.
Kindness does not mean you give away you rights. For creating a kind society Islam beleives much to have the best of people are the one who to serve in the government.