After the Rapture, God sends Two Witnesses to Jerusalem to speak His Word for three and a half years. The Witnesses never stop, and because they speak the truth to an evil, sinful world, they are hated. People try to kill them, but anyone who approaches them are killed by fire. At the appointed time, God allows the Beast to overcome the Two Witnesses and they lay dead in the streets for three and a half days, at which time they are supernaturally resurrected and ascend to heaven in front of the eyes of the world. (Revelation 11:3-15)
Speculation about the identity of the Two Witnesses abounds. Some think it would be Moses. However, there is a problem with that:
Since Hebrews 9:27 says "And inasmuch as it is appointed for men to die once and after this comes judgment," ...
So if one of the witnesses was Moses he would die twice... rendering the scriptures untrue. We know that is an impossibility! The only two men this is not the case for is Enoch and Elijah ... neither man died--
Genesis 5:24, "Enoch walked with God; then he was no more, because God took him away."
Second Kings 2:11, "...suddenly a chariot of fire and horses of fire appeared and separated the two of them, and Elijah went up to heaven in a whirlwind."
Enoch "walked with God for 300 years" (Genesis 5:23).
Also, God sent a prophecy:
Malachi 4:5-6 “See, I will send you the prophet Elijah before that great and dreadful day of the Lord comes. He will turn the hearts of the fathers to their children, and the hearts of the children to their fathers; or else I will come and strike the land with a curse.”
Just thinking out loud. The bible does not explicitly say who they are, so it will not be solved, but it is an exercise in curiosity. Now, as to witnessing: we cannot all be supernaturally powerful as the Two Witnesses in Revelation, but then again, we don't need to be. God will use us. He wants us to witness for Him and about Him. Tell of what He has done for you! Tell how you love Him! Just be yourself, and people will respond.