He believes it, the logic is just typical (twisted) fundanentalism.
My wife has an IUD and told me if she does get pregnant it will be an ectopic pregnancy due to the device. With the fertilized egg implanted outside the uterus there is zero chance of survival for the fetus (can’t grow a baby in a fallopian tube) and significant risk of internal bleeding and death for the mother.
All ectopic pregnancies are aborted at the earliest sign due to these extreme risks.
So you see, IUDs do cause abortions! Of newly fertilized eggs that never make it to womb and have a zero (0.000000000%) chance of survival.