Contradiction with Exodus 20:5
This verse speaks of God being jealous and punishing, in contrast to Isaiah 42:12, which emphasizes giving praise and glory to God.
Exodus 20:5: Thou shalt not bow down thyself to them, nor serve them: for I the LORD thy God [am] a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth [generation] of them that hate me;
Contradiction with Matthew 6:1
This verse warns against doing deeds to be seen by others, contrasting with the public declaration of God's praise in Isaiah 42:12.
Matthew 6:1: Take heed that ye do not your alms before men, to be seen of them: otherwise ye have no reward of your Father which is in heaven. [alms: or, righteousness] [of your: or, with your]
Contradiction with Isaiah 42:8
While Isaiah 42:12 calls for giving glory to God, Isaiah 42:8 states God will not give His glory to another, creating tension in the understanding of sharing God's glory.
Isaiah 42:8: I [am] the LORD: that [is] my name: and my glory will I not give to another, neither my praise to graven images.