What doctrine causes many people and preachers to stumble?
The doctrine of the Resurrection is the teaching that causes many people, including preachers, to stumble. The context identifies Christ's bodily resurrection as the doctrine that throws a curve for many, since it declares He arose from the dead bodily and showed Himself alive by many infallible proofs.
Les explains from Acts 1:3 that after His passion Christ showed Himself alive by many infallible proofs, being seen of them forty days. That period covers the time from the Resurrection until the Ascension, with ten more days until the Day of Pentecost. Les says the Resurrection is the doctrine that throws a curve in a lot of people, including preachers. Some may have problems with the virgin birth, yet they can swallow that more easily than the doctrine of His Resurrection—that He arose from the dead bodily. He notes a Muslim writer could not comprehend how God walked around in the flesh or how He arose from the dead and walked around bodily. The answer is, 'Because the Book says it.' Les also notes men have spent almost a lifetime trying to prove the fallacy of the Resurrection of Christ.