“For I was hungry and you gave me food, I was thirsty and you gave me drink, I was a stranger and you welcomed me.”

WASHINGTON — This passage from the Gospel of Matthew inviting us to welcome strangers into our midst could not be more salient than it is now, as our lawmakers embark on the long-awaited debate over immigration reform.

Senate hearings recently began after both President Obama and Sen. Marco Rubio of Florida made a strong call for comprehensive immigration reform during and after the State of the Union address. Their statements were encouraging, but lawmakers have their work cut out for them in the coming months — and millions of lives depend on reform.

Here’s the missing piece: Any discussion of immigration reform must recognize the international causes that drive unauthorized migration to the United States: hunger, poverty, lack of economic opportunity and inequality. Without addressing the root causes, the numbers of unauthorized immigrants in the United States will continue to rise.