This Bible contradiction is from the EvilBible.com.

Verses

Two sons

Galatians 4:22 View context

For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman.

Only one son

Hebrews 11:17 View context

By faith Abraham, when he was tried, offered up Isaac: and he that had received the promises offered up his only begotten [son],