Would you not agree that water is necessary for physical life? Without water, everything would die! Do you know that God is the source of spiritual life, Without Him, you cannot live eternal life? I'd like to take half a page to look at the corrilation of water to God...
Let's look at H2O. There are three forms of this chemical: liquid, solid, and vapor. The liquid is considered the default, fills any container, and is the source of physical life. The solid is the tangeable property (every tried to hold on to steam, or water for any ammount of time?), and in the olden days, you had to break a piece off to get some. The vapor is the power; think steam engine!
Now let's look at God. He has three forms: the Father, the Son, and the Holy Spirit. The Father is our creator; without him, we wouldn't exist (spiritual Water); He is willing to be with anyone. The Son, is God made man; He was broken and died so that we would not have to recieve our punishment and die (taking a piece of him is getting spiritual life). The Holy Spirit is God's power to help us through these days.
So you've learned that one H2O molecule can be either water, ice, or steam (ie conversely, three can be one), like God is the Father (Water), Son (Ice), and Holy Spirit (Steam). And I know that you've accepted water (or things containing water) for your physical life (which is the case because you are reading this); won't you accept Water for your spiritual life?