" there is one God and one mediator between God and men, the man Christ Jesus "1 Timothy 2.5
The word of God teaches us the will of God we must follow.According to this verse, the will of God is that Jesus has to be our only intermediary in front of him.God has not talked about another Biblical characters even if they have done many great things for him, even if he used them for doing many things on the earth.
Therefore, if during our prayer, we resort to another person not to Jesus for interceding for us before God, we sin.
And, if we sin when we pray, how God could easily hear us instead of "the prayer of a righteous man is powerful and effective." ( James 5.16 ) ?
1 Timothy 2.5