How does verse 5 indicate that the Ephesians had a responsibility to act?
Revelation 2:5 (ESV)
5Remember therefore from where you have fallen; repent, and do the works you did at first.If not, I will come to you and remove your lampstand from its place, unless you repent.
That the onus lies on the church in Ephesus to act (people are responsible!) is evident from the repetition of the word repent (both at the beginning and at the end of the verse).
5 Remember therefore from where you have fallen; repent, and do the works you did at first. If not, I will come to you and remove your lampstand from its place, unless you repent.