Did Jesus teach that we cannot serve both God and unrighteous mammon? Does that mean that money is second only to God in the list of things that influence us the most?

If these things are true, doesn’t it stand to reason that the misuse of or control of or exploitation of money might be the single most sought after target by any enemy of our wellbeing? And doesn’t that mean we ought to make it one of our priorities to see that these things never happen?