The doxology is three-fold. (See Note on Revelation 1:6.) It should run —
“Worthy art Thou, O Lord, and our God,
To receive the glory, and the honour, and the power,
Because Thou didst create all things,
And through (or, owing to — i.e., because of) Thy will they were (not ‘ are’) and were created.”
The existence of all things was owing to the will of God, as also was the creation of all things, which was the realisation or manifestation of that will.