Is there a restraining power on earth today that is holding back the Antichrist?
Yes. A restraining power is on the earth right now, holding back the Antichrist so he cannot be revealed ahead of God's time. It works like a dam in a river, ensuring the man Antichrist does not come on the scene until it is God's appointed time.
Les explains verse 6 as saying, "you know who withholdeth or restraineth, like a dam in the river," and that this one restrains so that the Antichrist might be revealed in his time, not ahead of time. Les teaches that there is a restraining power on the earth tonight making sure the man Antichrist does not come on the scene until it is God's time. The context does not further identify that restrainer; it only states that the restraint is real and active until God's appointed time.
And now ye know what withholdeth that he might be revealed in his time.