Romans 1:3,4:
Concerning his Son Jesus Christ our Lord, which was made of the seed of David according to the flesh;
And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead.

The resurrection of Jesus Christ is the whole keystone of Christianity.  It stands as the great fulcrum of what God wrought in Christ Jesus.  Matthew 27:45 says that when they crucified Jesus “there was darkness over all the land.”  The darkest days in the history of man were the three days Jesus Christ lay in the grave.  

But the greatest day was when the angel at the open sepulchre spoke the electrifying words, “He is risen.”

Matthew 28:5,6:
And the angel answered and said unto the women, Fear not ye:  for I know that ye seek Jesus, which was crucified.
He is not here:  for he is risen, as he said.  Come, see the place where the Lord lay.

The resurrection is attested to throughout the Word:

The knowledge of the resurrection of Christ was given to David by revelation.  Promises such as this one from Psalm 16 made it possible for Old Testament people to believe and to walk on God’s Word.  Peter is quoting it here on the day of Pentecost.

Acts 2:25,31:
For David speaketh concerning him, I foresaw the Lord always before my face, for he is on my right hand, that I should not be moved:
He seeing this before spake of the resurrection of Christ....

During his earthly ministry, Jesus Christ prepared his disciples for his coming death, but he also reminded them that it would be followed by his resurrection:

Matthew 16:21:
From that time forth began Jesus to shew unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day.

Matthew 17:22,23:
And while they [Jesus and his disciples] abode in Galilee, Jesus said unto them, The Son of man shall be betrayed into the hands of men:
And they shall kill him, and the third day he shall be raised again....

Luke 9:22:
Saying, The Son of man must suffer many things, and be rejected of the elders and chief priests and scribes, and be slain, and be raised the third day.

After Jesus Christ was raised from the dead, God’s spokesmen continued to declare his resurrection.  Peter spoke of it:

Acts 1:22:
Beginning from the baptism of John, unto that same day that he was taken up from us, must one be ordained to be a witness with us of his resurrection.

Acts 2:32:
This Jesus hath God raised up, whereof we all are witnesses.

Peter and John risked their lives to boldly declare it:

Acts 3:14,15:
But ye denied the Holy One and the Just, and desired a murderer to be granted unto you;
And killed the Prince of life, whom God hath raised from the dead; whereof we are witnesses.

The other apostles declared it also:

Acts 5:29,30:
Then Peter and the other apostles answered and said, We ought to obey God rather than men.
The God of our fathers raised up Jesus, whom ye slew and hanged on a tree.

After his conversion, Paul was faithful to speak of Christ’s resurrection:

Acts 13:29,30:
And when they had fulfilled all that was written of him, they took him down from the tree, and laid him in a sepulchre.
But God raised him from the dead.

By revelation, Paul wrote that in addition to making Jesus lord, believing in his resurrection makes salvation available:

Romans 10:9:
That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.

Because of the resurrection of Jesus Christ, we can now walk in newness of life:

Through the resurrection of Jesus Christ, we have the new birth.  As born-again believers, we can now walk in newness of life; and one day, when Jesus Christ returns, we will meet him in the air to ever be with him.

Romans 6:4,5:
Therefore we are buried with him by baptism into death:  that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.
For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection.

I Thessalonians 4:16,17:
For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God:  and the dead in Christ shall rise first:
Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air:  and so shall we ever be with the Lord.