Does a child go to heaven if he/she dies from a non-believer family, for example, a Muslim child who doesn’t have a concept of sin? Any reference verses to support the answer?
Yes, God gives salvation to those who die without an awareness of their sin, and the provision made for them through Jesus’ saving work. We can be assured of this for two reasons.
The first reason is that Scripture grants us clear examples of God making provision for people who were unable to repent and choose salvation. In the books of 2 Samuel and 1 Kings we are presented with two separate instances of boys who died in infancy (see 2 Sam. 11 & 12; 1 Ki. 12, 13, & 14:1–20). Both of these newborns died on account of heinous sins committed by their fathers (2 Sam. 12:13–14; 1 Ki. 14:11–13). The death of each child was a judicial consequence designed to impress upon their fathers the gravity of their sin and the reality that their sin would harm many people. What is noteworthy is that in both cases the Spirit of God clearly demonstrates that these infant boys were not regarded as condemned in any way but were entirely accepted by God (2 Sam. 12:15–24; 1 Ki. 14:12–13). On what account were they fully accepted by God? They were born in sin (see Ps. 51:5 & Rom. 5:12) and hadn’t had an opportunity to do anything good for God so why were they declared justified? The New Testament answers this question when it explains the saving work of the Lord Jesus who justifies the ungodly and provides salvation for those who don’t know that they need it (Rom. 4:4–5; 5:6–9).
This leads us to the second reason why we can be assured of God’s goodness to those who do not know Him: God is good (Ps. 119:69; Gen. 18:25). In fact, God is incredibly good! While His kindness leads the unbeliever to repentance, His goodness assures us that we are loved, desired, and accepted always (Jon. 4:9–11). His goodness watches over the unborn infant (Job 10:11–12), patiently pleads with the unrepentant sinner (Mt. 5:44–45), and daily draws the believer into increasing intimacy and enjoyment of Him (Ps. 23:6).