You asked

how does this teaching relate to the old testament's emphasis on loving one's neighbor as oneself?

Adds the setting and its conversation across both testaments.

Matthew 5:43-44

““You have heard that it was said, ‘You shall love your neighbor, and hate your enemy.’ But I tell you, love your enemies, bless those who curse you, do good to those who hate you, and pray for those who mistreat you and persecute you,””

This passage is part of Jesus' Sermon on the Mount, found in the Gospel of Matthew, likely compiled in the late first century CE. Jesus is presenting radical teachings to his Jewish followers, often building upon or reinterpreting existing Jewish law and tradition, encouraging a deeper, more demanding standard of righteousness.

What does it mean to genuinely love someone who actively seeks your harm?

Then — the setting

Jesus' teaching on loving enemies in Matthew 5:43-44 is part of the Sermon on the Mount, delivered to his disciples and a broader audience in Galilee around the early 1st century CE. The phrase "You have heard that it was said" refers to interpretations of Jewish law and tradition rather than a direct biblical quote. While Leviticus 19:18 commands 'love your neighbor,' the idea of 'hate your enemy' was an inference or a common sentiment of the time, perhaps found in texts like the Dead Sea Scrolls (e.g., the War Scroll), which encouraged hatred of specific enemies. Jesus' teaching radically challenges the prevailing social and religious norms, calling for an expansive love that extends beyond one's own community or those who reciprocate affection.

Across the Testaments

This New Testament teaching directly engages with the Old Testament command to 'love your neighbor as yourself' (Leviticus 19:18). While the Old Testament explicitly commands love for neighbors (which included fellow Israelites and resident aliens), it does not explicitly command hatred for enemies. However, it also includes commands for retribution and holy war against certain nations, which could have been interpreted as justifying antagonism towards enemies. Jesus' teaching here both affirms the core principle of love from the Old Testament Law and pushes it to an unprecedented extreme, demanding love even for those considered enemies. This deepens the Old Testament's ethical framework by extending the scope of 'neighbor' to include even those who oppose you, fulfilling and transforming the spirit of the Law rather than abolishing it.

Keep thinking

Read alongside it

Leviticus 19:18
This is the primary Old Testament source for 'love your neighbor as yourself,' which Jesus references.
Romans 12:14-21
Paul echoes and expands on loving enemies and returning good for evil.
Luke 6:27-36
Luke's parallel account of Jesus' teaching, emphasizing mercy and generosity even to the undeserving.

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