Ante does not just mean the adversary of (Christ) but also means in the room of / in the place of, the same root word is used here:
Matthew 2:22 But when he heard that Archelaus did reign in Judaea in the room of his father Herod, he was afraid to go thither: notwithstanding, being warned of God in a dream, he turned aside into the parts of Galilee:
Anti Christ I believe will try to deceive by claiming to be Christ or Christ's representative on earth, will prove this by performing miracles which counterfeit those of the apostles and Jesus Christ's
2nd Thessalonians 2:4 Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.
2nd Thessalonians 2:9 Even him, whose coming is after the working of Satan with all power and signs and lying wonders,
Revelation 13:11 And I beheld another beast coming up out of the earth; and he had two horns like a lamb, and he spake as a dragon.
Had the appearance of a lamb (Christ) but from the heart (i.e the words of his mouth cf Mat 15:18) his true satanic nature is discernible to those who have ears to hear.