For a great door and effectual is opened unto me, and there are many adversaries.
For a wide door of opportunity for effectual [service] has opened to me [there, a great and promising one], and [there are] many adversaries.
for a great door and effectual is opened unto me, and there are many adversaries.
In spite of the fact that there are many opponents, a big and productive opportunity has opened up for my mission here.
For a door, great and unavoidable, has opened to me, as well as many adversaries.
For a great door and evident is opened unto me: and many adversaries.
