Revelation 9:4, "They were commanded not to harm the grass of the earth, or any green thing, or any tree, but only those men who do not have the seal of God on their foreheads."
Ezekiel 9:4, "and the Lord said to him, "Go through the midst of the city, through the midst of Jerusalem, and put a mark on the foreheads of the men who sigh and cry over all the abominations that are done within it."
Is the "seal/mark" of God physical and visible in the natural? The mark of the beast is a counterpart to the seal/mark of God/The Holy Spirit. For we have been "sealed"
2 Timothy 2:18, "Nevertheless the solid foundation of God stands, having this seal: "The Lord knows those who are His,....."
Ephesians 1:13, "In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise,"
Ephesians 4:30, "And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption."
"Psalm 37:37, "Mark the blameless man, and observe the upright; For the future of that man is peace."
Why should we believe the mark of the beast is any more physical than the seal and mark of the Holy Spirit in/on believers? The mark of the beast is symbolic and it is spiritual. It is in the mind, which the unrenewed mind is the flesh and carnal nature and with it we give our worship and glory to God or with it in rejection of God, as even those who rejected their Messiah and by default worshipped the beast as those today who reject their salvation that do not have the mark or seal of God.