The central text of Christianity is probably the Gospel according to Matthew, and the core of the Gospel according to Matthew is probably the Sermon on the Mount. Within that, the two most important parts are probably the Beatitudes and the Our Father. However, these are both effectively summaries of Christianity, and both are essentially aphoristic – to understand them it helps to have significant context.
‘Give us this day our daily bread’ comes in the Our Father just after Jesus speaks of the new Kingdom and before he talks about forgiving. The obvious reference by ‘bread’ here is to the daily manna which sustained Moses and the ancient Israelites as they moved from political slavery (in ancient Egypt) to political freedom (in the promised land). This was a central event in ancient Jewish history, and Jesus consciously conceived of himself as the new Moses (of which Moses himself had prophesied). Many Jews of the time expected the new Moses to lead his people again to political freedom (this was part of what was expected by many of the ‘Christ’, or new king who was prophesied to be in the Davidic line and whose kingdom was to have no end – Jesus consciously was acting as both the new Moses and the new David). Jesus, however, considered his Kingdom spiritual instead of political (confounding many people’s expectations of what this new Kingdom would be like – ‘My kingdom is not of this world’). His purpose, rather, was to lead people from spiritual slavery to spiritual freedom (“Ye shall know the truth and the truth shall set you free.” John 8). Jesus is referring here, then, to a kind of manna that will help us as we move towards spiritual freedom – that’s the goal.
So, what is this new kind of manna or ‘bread’ which Jesus is referring to? Bread here is meant in an expansive sense, as all that nourishes us on a spiritual level. John 6:32 makes clear this spiritual sense of ‘bread’: “Moses gave you not that bread from heaven; but my Father giveth you the true bread from heaven.” Interestingly, with the daily manna of the ancient Israelites, they were only allowed to use it for that day, with the next day requiring a replenishing by God. Similarly, the focus here is on ‘this day’, and Jesus is saying that should be our focus in the spiritual life (see Matthew 6:34 “Worry not for tomorrow”). In particular, spiritual nourishment comes from a daily lived, experienced connection to God. This experience of God will refill and nourish us, spiritually speaking, and it is a major object of Christian practice to clear away the obstacles to this kind of daily connection.
Jesus emphasizes elsewhere in the Sermon on the Mount that we must ask, and the corresponding part in the Our Father is ‘give us’. Consider his discussion in the Sermon on the Mount where he says “Ask and it shall be given you” (Matthew 7:7) and then “What man is there of you, whom if his son ask bread, will he give him a stone?”, which ties that discussion even more clearly to this line in the Our Father about daily bread.
So, Jesus is here pointing out that we ought to ask, every day, for God to give us things that spiritually nourish us (love, divine wisdom, a connection with God and experience of Him, and so on) which will help us to move towards spiritual freedom, which is to say freedom from negative patterns of thought and action, and freedom to align ourselves with God’s will, that is, the Good – the new promised land.