Then Abimelech called Abraham and said to him, “What have you done to us? And how have I sinned against you, that you have brought on me and on my kingdom a great sin? You have done to me things that ought not to be done.” And Abimelech said to Abraham, “What have you encountered, that you have done this thing?”
Genesis 20:9-10 (NASB)
One of the most important lessons I had to learn as a Christian is that being "a believer" did not mean that I had the moral high ground.
It meant that I had to understand that I was morally accountable for my actions towards everyone.
Abraham is rightly rebuked.