What does it mean when Scripture says that Christ was the Lamb "slain from the foundation of the world" in Revelations 13:8?
Rob Ventura explains in this video that this verse explains how it was God's plan of salvation. This was God’s plan, that His Son would be slain. In the fullness of time, Christ would die on our behalf.
It was His eternal plan that His Son would be slain for sinners.
1 Peter 1:20-21 (NKJV) – “He indeed was foreordained before the foundation of the world, but was manifest in these last times for you who through Him believe in God, who raised Him from the dead and gave Him glory, so that your faith and hope are in God.”