Why was Jesus sorrowful at the Garden of Gethsemane? Does it show that He was unwilling or ignorant of the future? 

Those sentences which are colored in orange are from Maharishi Dayananda Saraswati book Satyarth Prakash (The Light of Truth) and those which are colored in black are Jerry Thomas’s response.

"And he took with him Peter and two sons of Zebedee, and began to be sorrowful and very heavy. Then saith he unto them, My soul is exceedingly by sorrowful, even unto death: tarry ye here, and watch with me. And he went a little further, and fell on his face, and prayed, saying, O my Father, if it be possible, let this cup pass from me: nevertheless not as I will, but as thou wilt." (26:37 – 39.)

C.  Now had he been the son of God and not an ordinary man and cognizant of the three periods of time or even a learned man, he would not have acted in the way he did. This clearly shows that all this fraud that Christ was the son of God, had knowledge of the future and could procure remission of sins was set up by Christ or his disciples. It is certain therefore that he was only an ordinary man, simple and honest but ignorant. He was neither a learned man nor a Yogi, nor one possessed of miraculous powers.

Answer: This passage very clearly shows that LORD Jesus Christ had the knowledge about the future precisely. In fact, He had precisely prophesized the manner in which He will die. Let us look at those passages beginning with this very chapter.

(a) LORD Jesus Christ precisely knew that He will be crucified (Matthew 26: 2).

(b) LORD Jesus Christ precisely prophesized that He will be betrayed (Matthew 26:21).

(c) LORD Jesus Christ also knew who will betray Him (Matthew 26:23).

(d) LORD Jesus Christ also knew that He will go to Galilee before disciples (Matthew 26: 32). In other words, LORD Jesus Christ knew that He will resurrect in a few days and not even weeks, months or years. Who can predict his own resurrection? In fact, He precisely told the days (Matthew 20:19).

(e) LORD Jesus Christ also knew that Peter would deny Him (Matthew 26:34).

The foreknowledge of LORD Jesus Christ can be denied only by a fool even if they examine only this chapter.

Further, it was not that LORD Jesus Christ was afraid of death. Had He been, the best thing to do was to leave the place. The very fact LORD Jesus Christ went to Garden of Gethsemane proves that He was willing to die.

So, what was that the LORD Jesus Christ was asking? What was the cup that the Heavenly Father had given to LORD Jesus Christ?

2 Corinthians 5:41 “2Cr 5:14 For the love of Christ compels us, because we judge thus: that if One died for all, then all died; and He died for all, that those who live should live no longer for themselves, but for Him who died for them and rose again.  Therefore, from now on, we regard no one according to the flesh. Even though we have known Christ according to the flesh, yet now we know Him thus no longer. Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new.  Now all things are of God, who has reconciled us to Himself through Jesus Christ, and has given us the ministry of reconciliation, that is, that God was in Christ reconciling the world to Himself, not imputing their trespasses to them, and has committed to us the word of reconciliation. Now then, we are ambassadors for Christ, as though God were pleading through us: we implore [you] on Christ's behalf, be reconciled to God.  For He made Him who knew no sin [to be] sin for us, that we might become the righteousness of God in Him.   

Here in this passage we read that God reconciled the world to Himself through making Him who know no sin as sin itself.

Ephesians 2: 14-16 “For He Himself is our peace, who has made both one, and has broken down the middle wall of separation, having abolished in His flesh the enmity, that is, the law of commandments contained in ordinances, so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross, thereby putting to death the enmity.

In other words, the only sinless person was made sin for our sake and He was punished for our transgressions. LORD Jesus Christ was praying about this cup.