2:25 God will mediate. Eli’s point is that while there may be some mediation of disputes between people, when someone offends God there is no one who can intervene. Eli’s sons sinned first and foremost against the Lord (v. 17), and they sealed their doom by refusing to hear Eli’s warning.

it was the will of the Lord to put them to death. This clear statement of God’s sovereignty over the destiny of the wicked does not diminish people’s responsibility for their own actions. An example of the relation between divine sovereignty and human responsibility is found in the hardening of Pharaoh’s heart in the early chapters of Exodus. About half the time Pharaoh is said to have hardened his own heart (Ex. 8:15); the rest of the time God is said to harden it (Ex. 4:21; Rom. 9:17, 18). God can punish persistent, willful sin by taking away the power to repent (Josh. 11:20; Rom. 1:24, 26, 28).