It is as if the Holy Spirit reproduces Jesus’ death and resurrection in our lives when we believe in Christ.  We become so unresponsive to the pressures, demands and attractions of our previous, sinful way of life, that Paul can say we are “dead” to those influences, because we have died with Christ (Rom. 7:6; Gal. 2:20; 5:24; 6:14; Col. 2:20).  On the other hand, we find ourselves wanting to serve God much more, and able to serve him with greater power and success, so much so that Paul says we are “alive” to God, because we have been raised up with Christ:  “We were buried therefore with him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life” (Rom. 6:4).  “So you also must consider yourselves dead to sin and alive to God in Christ Jesus” (Rom.  6:11; see also 1 Peter 1:3; 2:24).  Because we died and rose with Christ, we have power to overcome personal sin more and more (Rom. 6:12-14, 19); we have come to “fullness of life” in Christ (Col.  2:10-13); in fact, we have become a “new creation in him (2 Cor. 5:17, with vv. 14-15), and should therefore set our minds on things that are above, where Christ is (Col. 3:1-3).

And

“He who abides in me, and I in him, he it is that bears much fruit” (John 15:5).  It is not only true that we are in Christ; he is also in us, to give us power to live the Christian life.  “I have been crucified with Christ, it is no longer I who live, but Christ who lives in me” (Gal. 2:20).

And

“Be imitators of me, as I am of Christ,” writes Paul (1 Cor.  11:1).   John reminds us, “He who says he abides in him ought to walk in the same way in which he walked” (1 John 2:6).  So union with Christ implies that we should imitate Christ.  Our lives ought so to reflect what his life was like that we bring honor to him in everything we do (Phil. 1:20). Thus, the New Testament pictures the Christian life as one of striving to imitate Christ in all our actions. (sic)… in imitating him we are becoming more and more like him:  when we act like Christ we become like Christ.  We grow up into maturity in Christ (Eph. 4:13, 15) as we are “being changed into his likeness from one degree of glory to another” (2 Cor. 3:18).  The final result is that we shall become perfectly like Christ, for God has predestined us “to be conformed to the image of his Son” (Rom. 8:29; 1 Cor. 15:49), and “When he appears, we shall be like him” (1 John 3:2).  When this happens, Christ will be fully glorified in us (2 Thess.  1:10-12; John 17:10).

– all of the above can be found in Wayne Grudem’s Systematic Theology chapter 43 entitled Union With Christ.