Every word that he (Paul) has written, from his opening greeting onward, drives to this final summary. It all culminates right here in this statement: To God be the glory!
And there is kind of a threefold meaning and purpose behind this statement
First, it’s just Paul’s genuine overflow of worship!...
second ...it’s His expression of worship, but it’s also a call to us to worship!...
And then finally, it is an affirmation, a statement of confidence that this will, in fact be true.