What RTB proposes is that God, being a good Engineer, reuses good designs. If, for example, ERVs work in the genome, then why not give it to other similar creatures that would need to fight off viruses. These were not implanted by viruses but were given by God to allow man and other mammals to fight off infection because they break the cycle within the virus.

To me, the atheist/evolutionists (definitely not all scientists) are like listening to a twisted lawyer present his case purposely leaving out details to support the conclusion and the whole of the courtroom believing it because they are sold out on the eloquent speech. In this case, it is because man likes to sin and he likes the idea that the Bible might not be true and God might not be real so that he can continue in his sin without eternal consequence. What a shocker to meet God face to face on the day of judgment.