Why did Christ have to die and be raised from the dead?
Christ had to die, be buried, and be raised from the dead for our justification. The Law was given to prepare for the Messiah so He could fulfill the work of the Cross, satisfying and paying the Law in full. Salvation is by faith plus nothing in His finished work, all in God's predetermined counsel.
Les teaches that the Law was intended to prepare Israel for the coming Messiah, so that when He came they could be ready and believe everything He was. Most of the nation rejected it, but the concept remains valid: the Law was given to prepare everything for the coming of the Messiah, that He could fulfill the work of the Cross. Yes, He had to die, be buried, and be raised from the dead for our justification. Now the Law has been satisfied and completely paid in full through the work of the Cross, so we enter in by faith plus nothing. The Law has done its job, been crucified, and is off the scene, all in the predetermined counsel of God. Les also explains that believers become children of God by faith in Christ Jesus, not by keeping the Law. Paul's phrase "by faith in Christ" refers to the finished work of redemption: the fact that Christ died and was buried and rose again.