The Bible tells us that God has revealed something of himself to everyone in the natural order. There is a sense in which everyone has therefore heard about God, and no-one (except perhaps children) has an excuse for not seeking him out and acknowledging him properly. The problem is that we all suppress this truth in one way or another in order to believe what we want to believe and behave as we want to behave. This is why God sent Jesus to call us back to him and enable us to be forgiven.
The Bible is clear that everyone therefore needs to respond to Jesus and that only those who place explicit faith in him can be confident that they are forgiven and will receive everlasting life. It is also clear that people cannot be saved by trusting their preferred view of God or by assuming they can ever be good enough to deserve his acceptance.The key question then is whether some can, without hearing of Jesus, come to a good enough knowledge of God to rely on him alone for these things. The Bible suggests otherwise. Yet we can be reassured that God is well able to ensure that those who would believe do receive explicit knowledge about Jesus in order to do so. The Bible does record an instance when Jesus actually spoke to one non-Christian from heaven, and others where God audibly commands and sends Christians to speak of Jesus to particular people.
The important thing is that you respond to what you have heard and not use this question as an excuse for inaction.
(Romans 1:18-3:21, 10:13-15, John 3:16-21, 4:20-26, Acts 9:1-22, 10:9-48)