The rationalist demand nothing short of empirical evidence, from believers, for the existence of God, and all their religious claims. I suppose that if someone claimed to know a person who was able to levitate from a sitting position and remain suspended in the air, you would remain disbelieving until you witnessed it for yourself. After all, seeing is believing. Yet, think of the apostle Thomas refusing to accept that Jesus had risen from the died unless he saw for himself. Then Jesus told him, "Because you have seen me, you have believed; blessed are those who have not seen and yet have believed." Jo. 20:29
But the Lord wants us to believe - to know him and his love for us. Indeed, the Lord wants to, and will "show" us, if we will let him. There is a big difference between demanding him and letting him show us. If someone love us we will not know this until they begin to show us their love. They initiate the revelation of their love in ways that are uniquely their own, but are tailored in such a way as to make it possible for us to see and accept the fact of their love. It remains for us to accept or reject their love.
It may be that another person tells us that someone loves us. We in turn can make ourselves available, in anticipation of a personal experience to the truth of that love. Here we have a good description of what is meant by personal prayer, "opening ourselves to the experience of God's love".
In psalm 139, we see someone who has come to know, in a deep and personal way, his status in God's eyes. How did he come to this knowledge? Only God could have reveal this to him. He had opened his mind and heart and God showed him.
This is a wonderful text to take to prayer. Think of these verses of the psalm as God's words to you. This is how God's voice sounds, gentle, personal, loving. Let this voice speak to you.
LORD, you have probed me, you know me:
you know when I sit and stand;
you understand my thoughts from afar.
You sift through my travels and my rest;
with all my ways you are familiar.
Even before a word is on my tongue,
LORD, you know it all.
Behind and before you encircle me
and rest your hand upon me.
Such knowledge is too wonderful for me,
far too lofty for me to reach.
Where can I go from your spirit?
From your presence, where can I flee?
If I ascend to the heavens, you are there;
if I lie down in Sheol, there you are.
If I take the wings of dawn
and dwell beyond the sea,
Even there your hand guides me,
your right hand holds me fast.
If I say, “Surely darkness shall hide me,
and night shall be my light”
Darkness is not dark for you,
and night shines as the day.
Darkness and light are but one.
You formed my inmost being;
you knit me in my mother’s womb.
I praise you, because I am wonderfully made;
wonderful are your works!
My very self you know.
My bones are not hidden from you,
When I was being made in secret,
fashioned in the depths of the earth.
Your eyes saw me unformed;
in your book all are written down;
my days were shaped, before one came to be.
How precious to me are your designs, O God;
how vast the sum of them!
Were I to count them, they would outnumber the sands;
when I complete them, still you are with me.
When you would destroy the wicked, O God,
the bloodthirsty depart from me!
Your foes who conspire a plot against you
are exalted in vain.
Do I not hate, LORD, those who hate you?
Those who rise against you, do I not loathe?
With fierce hatred I hate them,
enemies I count as my own.
Probe me, God, know my heart;
try me, know my thoughts.
See if there is a wicked path in me;
lead me along an ancient path
"Such knowledge is too wonderful for me, far too lofty for me to reach."
Your eyes saw me unformed; ... my days were shaped, before one came to be.