If your answer is yes to this question, is it because you think you will have to change and become something you don't want to be, and there will be no way back? Is it because you think somehow you will lose something of yourself, or take on a religious identity you just don't want?
I understand saying "yes" to God in the terms of a perfect analogy.
Do you remember when you were a child trying to do things to please your parents?
Or, if you were unfortunate enough not to have had such a childhood, could you remember in your suffering years of neglect, of yearning to have had such parents to love and care for you that it would have drawn from you the desire to please and love them?
The natural thing for every child is that every child should grow and develop in the light of such parental love.
To say "yes" to God is just like that. It is the next step beyond childhood.
It is to recognise God as our Universal Father, the One Who has brought us all into being, as our Generator Source, the One Who has brought us all into His whole One-Creation, with every person having the natural capacity to come to discover and to know and understand Him as being the true Father of us all.
We then, come to see Him, no matter how old we are, we see Him as our Father-generator, our true 'Daddy', who we come to love as our Total Benefactor, Who has given us all that we are, to live and to be, and to know, and to share in the incredible wonder of the life and the love of His own Eternity. He has given us all to share in the wonder, as Our Father; to share in the wonder of His own life and Being, of what it is to live and to be, when before He gave us our life, we were not and never would be.
He has said, in His Scriptures, "Unless you become as a little child", to come to know Me from the point of view of a little child, "You cannot enter into My family Kingdom of Heaven." (Mark 10:15)
This is our natural place in His Life. He is Our Father. We are His 'children'. (Acts 17:27-28)
So, do not be afraid to say "yes", to your Father Who loves you, Who created you in His love. Your Father Who says to you, "Before I created you in your mother's womb, I knew you." (Jeremiah 1:4-5) "Come to Me!" (Matthew 11:28)
So, dear child of the Eternal One, the "I-Am-Who-Am", the "He-Who-Is", come and love Him as your own loving parental Father, and you will never stop loving and wanting to please Him. He calls you to live and to share forever in the wonder and security of His world of unending parental love.
So, "Do not be afraid!" (John 6:20) "Come..."
Note: See also - A Call to Life.