Firstly, Shylock is a very devout Jew and he despises Christians. His intense dislike sprouts from the abuse that he has suffered at their hands, especially from Antonio. His loathing for them is patently apparent in Act 1, scene 3 when he tells Bassanio:
...I will buy with you, sell with you, talk with you,
walk with you, and so following, but I will not eat
with you, drink with you, nor pray with you.
He clearly does not want to associate with Christians. He further expresses his abhorrence later in Act 2, scene 5 when he informs his daughter, Jessica:
I am bid forth to supper, Jessica:
There are my keys. But wherefore should I go?
I am not bid for love; they flatter me:
But yet I'll go in hate, to feed upon
The prodigal Christian.
It is obvious that Shylock thinks Christians are irresponsibly wasteful and will only entertain their requests for his own benefit. The discovery that his daughter has eloped with a Christian would thus be a shock to him in this regard. He would obviously be exceedingly angry since he would believe that Jessica has betrayed him— which is exactly what happens when he later discovers that she has eloped with Lorenzo, who is a Christian.
In Act 4, scene 1, in court, he also declares his dismay at Jessica having married a Christian:
These be the Christian husbands. I have a daughter;
Would any of the stock of Barrabas
Had been her husband rather than a Christian!
The Biblical reference is to Barabbas, a notorious criminal, who had been chosen over Jesus Christ by the Jewish crowd to be released by Pontius Pilate, leading to Christ's crucifixion.
What also makes Shylock angry is that Jessica stole some of his money and precious jewels when she eloped with Lorenzo. He declares his anger and frustration at his daughter's deceit to Tubal in Act 3, scene 1:
Why, there, there, there, there! a diamond gone,
cost me two thousand ducats in Frankfort! The curse
never fell upon our nation till now; I never felt it
till now: two thousand ducats in that; and other
precious, precious jewels. I would my daughter
were dead at my foot, and the jewels in her ear!
would she were hearsed at my foot, and the ducats in
her coffin! No news of them?...
It seems as if Shylock cares more about his possessions than he does about his daughter. It is shocking that he states that he would rather see her dead and his jewels in her ear so that he could retrieve them. He also complains about the fact that he has to spend money in searching for her, which he calls a "loss upon loss." He pities himself and is remorseless in his criticism of Jessica and the hunt for his precious belongings.
His obsession with material wealth and his anger at being robbed by his own daughter is clearly displayed further in Act 3, scene 1, as illustrated by the following excerpts when Tubal informs him about Jessica spending his money and giving away his jewels:
Thou stickest a dagger in me: I shall never see my
gold again: fourscore ducats at a sitting!
Out upon her! Thou torturest me, Tubal: it was my
turquoise; I had it of Leah when I was a bachelor:
I would not have given it for a wilderness of monkeys.
Shylock's behavior is clearly not that of a loving and caring parent, but rather of a man obsessed with possessions and material wealth.