“For the Jews require a sign, and the Greeks seek after wisdom.” (1 Corinthians 1:22)
There are signs in the Old Testament so we could have the Word. That is, so the Jews would write it down. God does the first miracles, or signs, so they’ll know it is God. After Moses and Joshua, for a period of 430 years there are no signs because they were given the Law (It was written). Then the prophets Elijah and Elisha, whom God did miracles with. Then, no more signs until Jesus and the Apostles. In each period the signs lasted for 2 generations. The Apostles did signs to confirm the truth and power of the gospel because the New Testament had not yet been written. From Moses to Jesus, signs were so the Jews would believe but they didn’t. The antichrist will deceive by signs and wonders because the people will have not believed the Word of Truth.