In the verse “if we died with Him, we will also live with Him,” the words “with Him” are key. We can only live with Christ if we are united with him in his death. In dying for us, Christ received the wages that were due to us because of sin (Rom 6:23). It is by his death that we are reconciled to God (Eph 1:7, Rom 3:24) and through his death that we have access to God’s Spirit and grace (Rom 5:1-2, Rom 5:15).
To be baptized into Christ is to be baptized into his death (Rom 6:3). Baptism therefore constitutes the first way in which we die with Christ.
That one died for all, therefore all died – 2 Cor 5:14
But baptism is just the first step in the life of union with Christ. It marks the beginning of a new way of walking (Rom 6:4-6) in the Spirit of Christ that is, at the same time, a dying to the flesh and sin (Rom 8:13, Gal 5:16-17). Paul admonishes us not to “receive the grace of God in vain” (2 Cor 6:1). The grace that Christ wrought for us through his death is meant to bear fruit in our lives, bringing about true transformation, holiness, and an obedience that comes from the heart (Rom 6:17).
So then, brothers and sisters, we are under obligation, not to the
flesh, to live according to the flesh— 13 for if you are living in
accord with the flesh, you are going to die; but if by the Spirit you
are putting to death the deeds of the body, you will live – Rom
8:12-13
To Paul, dying with Christ also meant the literal experience of suffering, persecution, and death for the sake of Christ and the salvation of souls. This is the meaning in the context of 2 Tim 2:11.
For this reason I endure all things for the sake of those who are
chosen, so that they also may obtain the salvation which is in Christ
Jesus and with it eternal glory. – 2 Tim 10
The union between Christ and those who are persecuted for his sake is richly implied in Christ’s words to Paul on the road to Damascus: “I am Jesus whom you are persecuting” (Acts 9:5). The impact these words had on Paul is reflected, I think, in how he viewed his own sufferings and tribulations.
We are afflicted in every way, but not crushed; perplexed, but not
despairing; 9 persecuted, but not abandoned; struck down, but not
destroyed; 10 always carrying around in the body the dying of Jesus,
so that the life of Jesus may also be revealed in our body. – 2 Cor
4:7-10
As a final thought, in the mystery of our union with Christ, “the mystery that is Christ in you,” lies the “wealth” and “the hope of glory” (Col 1:27). To die with Christ ultimately means to remain united with him until the end, when the life that we are given to live with him will be our eternal life with God (Rom 2:7, Rom 6:22).