If Islam is a religion of peace, then why violence verses are there in the Quran? How can Muslims justify this?
There are many verses which says, catch them, kill them, slaughter them but...
To understand those verses, you need to read before and after to clarify the context of the matter.
Specially people talk about Surah Tawbah 9/5: And when the sacred months have passed, then kill the polytheists wherever you find them and capture them and besiege them and sit in wait for them at every place of ambush. But if they should repent, establish prayer, and give zakah, let them [go] on their way. Indeed, Allah is Forgiving and Merciful.
This is what you are talking about, but why? Do you know what they did before, read about Sumaiyah RA., Bilal (RA), they went till Madinah to kill Muslims (Junge Badar, Uhad ...). It is not about the disbelievers but for those oppressor who try to destroy the peace in the area.
At the end of those ayah, Allah is Forgiving and Merciful.
No. Quran doesn’t Sanction Violence against “Unbelievers” nor it’s the teaching of Islam. The fundamental Quranic principle is that fighting is allowed only in self-defense, and it is only against those who actively fight against you. Indeed, Islam is the religion that seeks to maximize peace and reconciliation so as to establish the justice on earth.
If mother teaches her child to help someone or help a weak child who cannot fight for his rights. So she is teachings high moral values so that he becomes responsible child, not just self-centred but considerate and caring. Same way the security of police has been appointed to help the victim and weak person to support them. Allah is Just He loves justice which the prime teachings of Islam. Islam is the religion of peace only in a sense if followed properly.
“The Holy Quran clearly says that ” If you have killed even a single person , you have killed the whole humanity” (Quran Surah maida)
By the above verse the Quran is actually promoting humanity and showing how important a human life is. It’s greater than Worship to save human life. But when it comes to justice Quran says :
"O you who have believed, be persistently standing firm in justice, witnesses for Allah , even if it be against yourselves or parents and relatives. Whether one is rich or poor, Allah is more worthy of both. So follow not [personal] inclination, lest you not be just. And if you distort [your testimony] or refuse [to give it], then indeed Allah is ever, with what you do, Acquainted". (Quran 4:135)