Why Do I Have to Bear My Own Load?

Can any mere creature pay for me?

No.

• To begin with, God will not punish any other creature for what a human is guilty of.

It would be unjust.

• God entered into a covenant with man, whom He made in His own image. 
• Man alone was created able to render obedience to God's demands.
• Man alone disobeyed.  
• It would be unjust if God punished another creature for the sins which man committed.

I may ask, "What about the sacrifices in the Old Testament?"

• These sacrifices were never offered as a payment for sin.
• They were symbols pointing ahead to the only sufficient sacrifice which could pay for sin: the sacrifice of Christ, the true Lamb.

Moreover, 

• even if an animal could die for me and make payment to release me from the kingdom of Satan, 
• it could not make payment required for admission into the kingdom of God, 
• for an animal cannot render obedience to God's commandments. 
• It must be man who makes payment. 

Ezekiel 18:4,20  

• Behold, all souls are Mine; the soul of the father as well as the soul of the son is Mine; the soul who sins shall die.  
• The soul who sins shall die. The son shall not bear the guilt of the father, nor the father bear the guilt of the son.  The righteousness of the righteous shall be upon himself, and the wickedness of the wicked shall be upon himself.

Hebrews 2:14-18  

• Inasmuch then as the children have partaken of flesh and blood, He himself likewise shared in the same, that through death He might destroy him who had the power of death, that is, the devil,
• and release those who through fear of death were all their lifetime subject to bondage.  
• For indeed He does not give aid to angels, but He does give aid to the seed of Abraham.  
• Therefore, in all things He had to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God, to make propitiation for the sins of the people. 
• For in that He Himself has suffered, being tempted, He is able to aid those who are tempted.

Adapted Excerpt from Only By True Faith by Van Delden

Heidelberg Catechism Lord's Day 5