John Chrysostom

What I had before occasion to remark, that I mention here too, that he continually digresseth into exhortation, without making any twofold division as he does in the other Epistles, and setting apart the former portion for doctrines, and the latter for the care of moral instruction. Here then he does not do so, but blends the latter with the subject throughout, so as to gain it an easy admission. …

Homily on Romans 11 ↗

Theophylact of Ohrid

He did not say: partook of the likeness of His death, but says "united," indicating by the word "union" the fruit of Christ's death in us. The body of Christ, buried in the earth, brought forth the fruit of salvation. Since we are buried in water, while Christ in the earth, and moreover we are buried to sin, while He in body, he did not say "death," but "the likeness of death." Therefore we shall also be partakers of the resurrection, inheriting eternal life, as those who have shown forth the resurrection consisting in good works.

Commentary on Romans ↗

Thomas Aquinas

Then when he says, for if we, he shows how the consequence follows necessarily. For after he died, Christ arose; hence it is fitting that those who are conformed to Christ's death in baptism should be conformed also to his resurrection by leading a blameless life. …

Commentary on Romans ↗