This question came up at the White Horse Inn last week. 
Did God renege on his promise to Eli? (1 Sam 2:27-36)
This is a significant question because of what God says elsewhere about his character. For Numbers 23 describes God as a promise keeper:
NIV Numbers 23:19 God is not a man, that he should lie, nor a son of man, that he should change his mind. Does he speak and then not act? Does he promise and not fulfill?
Is is possible that God doesn’t always keep his promises?
A few thoughts:
1. In verse 30 ‘I promised’ could be an overtranslation. It is literally just ‘I said’. We don’t seem to have an oath or covenant here. Could this have been a more conditional arrangement? We don’t have a record of God’s original word to Eli.
2. Eli’s ancestor Aaron and his descendents were appointed and anointed as a priest/s forever (Ex 28:1ff, Lev 8:1ff). Despite Eli and his family losing the priesthood (See 1 Kings 2:27), the Aaronic priesthood continued through others. This attests to God’s faithfulness to his original plan.
3. Eli and his son’s faults were so bad they compelled God to remove them from the priesthood:
○ Eli failed to honour God above his sons (1 Sam 2:29)
○ He failed to restrain his sons (1 Sam 3:13)
○ Effectively Eli despised God (1 Sam 2:30)
4. Ultimately God showed himself faithful and committed to his creation and his people by appointing Jesus to be the perfect High Priest (Heb 5-9). ‘Jesus has become the guarantee of a better covenant (Heb 7:22)
5. The passage in 1 Sam 2 warns us that we cannot presume on God. We cannot continually despise him and expect his goodwill. For those of us who have though, forgiveness is always available. As Hebrews says, Jesus always lives to intercede for us (Heb 7:25).