Good letter.
For your Dad:
(Romans 12:2) And quit being fashioned after this system of things, but be transformed by making YOUR mind over, that YOU may prove to yourselves the good and acceptable and perfect will of God.
PROVE to yourself.
(Acts 17:11) Now the latter were more noble-minded than those in Thes·sa·lo·ni′ca, for they received the word with the greatest eagerness of mind, carefully examining the Scriptures daily as to whether these things were so.
CAREFULLY EXAMINING ... WHETHER THESE THINGS WERE SO.
Ronald Reagan referring to Russian saying: "Trust, but verify."