"Indeed, those who have believed (in Prophet Muhammad PBUH) and those (before Him) who were Jews or Sabeans or Christians, those who believed in Allah and the Last Day and did righteousness - no fear will there be concerning them, nor will they grieve." (Qur'an 5:69)
"Indeed, disbelievers are those who said: "Allah is the third of the three (in a Trinity)." But there is no God but Allah. And if they cease not from what they say, indeed, a painful torment will befall the disbelievers among them." (Qur'an 5:73)