I had passively called God "dad" from time to time throughout my walk, but never as "the title" I referred to him by. When I would call him dad, I'd use the title "Father", and one time in a prayer session the Holy Spirit showed me how disingenuine that phrase was (to me). I never even called my earthly dad "father", and this title wasn't coming out of love, it was coming out of a religion. And that's when things started to click for me.
The Holy Spirit showed me how I was just using religious phrases to speak to him, the whole reason God has the title "Father" is for us to come before him as his children! The Lord revealed to me that to call him "Father" doesn't mean you literally call him "Father", it means you refer to him as your father. You give him the respect, and place in your life as a father. This all revolves around the title, I called my earthly father “dad”, so why not give God that exact title.
The more God broke this down to me, the more I realized how much love was behind this genutine title of dad. To me, the title of "dad" meant comfort, help, love, mercy, kindness, and protection. In my youth I had a desire to receive these things from a father, and spent my whole life just concealing it, but it wasn't until I knew God personally that I discovered God as my DAD. All these desires were bubbling up in my heart and when I began to passively refer to God as dad, my heart came to him as a son. So much healing and comfort came after I started giving him the title my heart knew a father as, dad.
What title does your heart give a "father", is it pops, dad, pop, pappa, daddy, father? Give God that title and give him your heart as a child would their father! I can't leave out the elephant in the room, at first there was an "earthly" remembrance that was tied to that title of "dad". My earthly experiences changed my heavenly expectations, and I had to let God bring healing in my heart before that title of "dad" unlocked it's full potential. Maybe you never knew your father, or went through a rough relationship with them.
Luke 11:11 "If a son asks for bread from any father among you, will he give him a stone? Or if he asks for a fish, will he give him a serpent instead of a fish?"
I really encourage you to read the blog linked below to discover how God's word counsels us to receive Him as our father.