... Similarly, we should not think that Jesus was able to live without sin because he was God, while we cannot because we are mortal. Hiding behind this view is partly a wrong view of sin and partly a wrong view of Jesus. The wrong view of sin is the one that views sin in terms of absolute perfection against an absolute standard, as if God is a legalistic accountant of some kind.
Did Jesus ever accidentally "wrong" someone by forgetting to meet them at sunrise to fish on the Sea of Galilee? Did he make them wait? Obviously we don't know. But if he did, this is probably not what Hebrews had in mind when it said Jesus was without sin (Heb. 4:15). Paul does at some points at least seem to invoke an absolute standard in order to do away with it (e.g., Gal. 3:10), but this is not the primary standard of sin in Scripture--or within Judaism at the time.
The normal sense of sin was that of intentionally wronging God or another, intentional wrongdoing. This is surely the sense of sin that is primary in Scripture, and it is arguably this sense of sin that Paul had in mind when he said that Jesus "had no sin" (2 Cor. 5:21). Arguably Jesus was a model for us in this sense of sin--that by the power of the Holy Spirit we can also follow Jesus' example. As 1 John 3:9 puts it: "No one who is born of God will continue to sin, because God's seed remains in them." This is not an expectation of absolute perfection. It is about being able to follow through with a heart that intends to do the right thing.
Can we do miracles today? The perspective of Scripture and Christian history gives a "yes" answer. From a Christian perspective, we live in the same part of history that Jesus inaugurated. Jesus may not appear to people in the same way today as he did the apostles. In that sense we can question whether there are any apostles today of the sort we find in the New Testament. But the Spirit has arguably continued to work miracles throughout history, and Christians believe we have that same Spirit today.
A person can both over- and under-emphasize such things. A person can miss opportunities because of a lack of faith, and a person can get preoccupied with "signs and wonders." Jesus flatly refused to do signs on demands. "No sign will be given," he flatly says at one point (Mark 8:12). Similarly, those who refuse obvious medical treatment arguably reject an offer of healing God has brought through a knowledge of his own creation.
The key is to recognize that Jesus' humanity was not only a true humanity, but a perfect indication of what humanity can be and was supposed to be. We should not read the story of Jesus as something beyond the reach of the rest of us through the power of the Spirit. And we should not idealize him in a way that takes him beyond the realm of true humanity...