Was Jesus obligated to answer the High Priest that he was the son of God? In Matthew chapter 26 Caiaphas when questioning Jesus adjured him to declare whether or not he was the son of God. 

Mat 26:63 and 64  KJV  


  But Jesus held his peace. And the high priest answered and said unto him, I adjure thee by the living God, that thou tell us whether thou be the Christ, the Son of God. Jesus saith unto him, Thou hast said: nevertheless I say unto you, Hereafter shall ye see the Son of man sitting on the right hand of power, and coming in the clouds of heaven. 


According to Merriam Webster Adjure is defined as:


  ADJU'RE, v.t. [L. adjuro, to sweat solemnly, or compel one to swear; from ad and juro, to swear.]


1. To charge, bind or command on oath, or under the penalty of a curse.

2. To charge earnestly and solemnly, on pain of God's wrath.

    1. ***I adjure thee by the living God. Mat 26.***

3. To conjure; to charge, urge or summon with solemnity.


The original Greek word translated adjure was:

ἐξορκίζω exorkizo (ex-or-kid'-zo) v.1. to exact an oath, i.e. conjure

    [from ἐκ ek (ek) (or  ex  ex) prep. And ὁρκίζω horkizo (hor-kid'-zo) v.]

        KJV: adjure
It doesn't posit much difference in the meaning even if you use all the words such as forced, compelled, adjured, demanded, charged, obligated etc. The whole idea is that the high priest was looking for a way to force Jesus condemn himself to death. Many accusers came forward but no one was able to find any appropriate charges to put Jesus to death. The high priest, knowing that Jesus would not lie in the name of God, forced Jesus to confess in public that he was the Son of God. According to Jewish Law, blaspheming God deserved a death punishment. When Jesus admitted that he was the Son of God, the high priest now got the opportunity to sentence Jesus to death.

The sad side of this story is that even though they knew that Jesus would not lie when swearing in the name of God, they took Jesus' answer as blasphemy. Their hearts were hardened. They could not see the Messiah standing before them but they only saw a man claiming to be the Messiah.