Aquinas said that we can only say what we think about the Divine but when we think we've really got an understanding of God all we have is an idea regarding something but it's not God .  
The commandment is to love God .  We do that especially at prayer and the deeper the prayer the deeper the love .
We who are human scarcely know what it is to be truly human .  How much less do we know what it is to be divine  ?  
Scripture tells us repeatedly " they came to believe ..." .  
It is a life of faith not memorizing formulas to pass a test and be rewarded with the reception of a sacrament .
A 7 year old is beginning to grasp cause and effect =  age of reason .   If one's understanding of anything freezes at age 7 ...   how sad .  
Life and life in abundance !