Quran 2 : 217.
English Translation (The Noble Qur'an)
"They question thee (O Muhammad) with regard to warfare in the sacred month. Say: Warfare therein is a great (transgression), but to turn (men) from the way of Allah, and to disbelieve in Him and in the Inviolable Place of Worship, and to expel his people thence, is a greater sin with Allah; for persecution is worse than killing."

"And they will not cease from fighting against you till they have made you renegades from your religion, if they can. And whoso becometh a renegade and dieth in his disbelief: such are they whose works have fallen both in the world and the Hereafter. Such are rightful owners of the Fire: they will abide there in."

Where does it say that killing is allowed??
Get a quran with english interpretation and research the paras which make you feel uneasy about islam.
It will be more helpful in understanding Islam better

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