Then why isn't everyone who hears or reads it converted?The enabling power comes from the Gospel, the power of God unto salvation.
Must be called to be of the promiseFor the promise is to you and to your children, and to all who are afar off, as many as the Lord our God will call.”
Who were they who "gladly received his word"? Obviously, not everyone or that statement would not have been necessary.
[Act 13:48 KJV]
48 And when the Gentiles heard this, they were glad, and glorified the word of the Lord: and as many as were ordained to eternal life believed.