And we rejoice in the hope of the glory of God. Not only so, but we also rejoice in our sufferings (Rom 5:2-3), …
To rejoice in your sufferings is not to rejoice over the sufferings per se. No, every suffering you experience while living on earth comes from Satan, whether it is sickness, poverty, or a bad human relationship that causes you to suffer. Such sufferings cannot make you rejoice, and you should not thank God for them. You can only thank God for what he does and what he gives. He is not the author of any suffering. Knowing this truth, you can still rejoice in your sufferings as the above scripture says. Paul explains the reason for it as follows:
… because we know that suffering produces perseverance; perseverance, character; and character, hope. And hope does not disappoint us, because God has poured out his love into our hearts by the Holy Spirit, whom he has given us (Rom 5:3-5).
What you need to realize is that the kinds of sufferings Paul has in mind are mainly those of persecutions, or hardships that he experiences in preaching the gospel. Note the way he points our attention to the love of God, which was poured out into our hearts by the Holy Spirit. He argues that because of this love, he can go on to preach the gospel in spite of all these sufferings—the persecutions. It is God’s love that actually compels him to preach, and gives joy and strength to overcome such hardships.
James writes in the similar way:
Consider it pure joy, my brothers, whenever you face trials of many kinds, because you know that the testing of your faith develops perseverance. Perseverance must finish its work so that you may be mature and complete, not lacking anything (James 1:2-4).
Here, sufferings are expressed as “trials of many kinds” in a more general sense. They are trials because they challenge your faith to test you. Note that he, too, speaks about “perseverance,” through which you will grow up to be “mature and complete”—something Paul expresses as “character.” Therefore, James urges believers to “consider it pure joy” when facing such trials and sufferings. For Christians, there is really nothing to be afraid of. All things, even though they look destructive, are constructive in God.
This truth, if you accept it by faith, will change the way you live on earth. Without faith in God’s creation work, you will always be afraid of sufferings and will need to run away from them instead of facing them, because for those who have no faith in God’s goodness and power of creation, sufferings are considered merely works of destruction. See, for instance, the following words of Paul:
That is why, for Christ's sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong (2 Cor 12:10).
What he lists here are all works of destruction—“weaknesses,” “insults,” “hardships,” “persecutions,” and “difficulties.” Paul went though all these works of destruction, and became weak physically and even mentally. Nevertheless, he says, “When I am weak, then I am strong.” It means that even if he feels and looks weak, but he is actually strong in God who gives him strength.
The Greek word for “weakness” is astheneia, and many think that it refers to some kind of a chronic disease Paul had as the following verse seems to suggest:
To keep me from becoming conceited because of these surpassingly great revelations, there was given me a thorn in my flesh, a messenger of Satan, to torment me (v.7).
This theory implies that God sometimes leaves people sick, and in such cases, it is God’s will for them to be sick: no matter how hard they pray, they will not be healed. Accepting this idea, Christians often pray, “If it is your will …” But the key to understanding what Paul really means lies within the context of the whole passage. You will need to go back to ch. 11, and find out what he means by “weakness.”