Energeia: a working in the power of anything.
The present tense is used here as stating the moral fact; it is not present as to time. It refers to the time when the lawless one is revealed, and is in contrast to the present time, which is referred to in v. 7.
'The obtaining of the glory' is without the article in Greek. With the article it would refer to the fact of obtaining the glory; without it, it is the character of the calling: 'to obtaining glory.' What that glory is is then stated: 'that of our Lord Jesus Christ.' 'We are called to obtention of glory, [that] of our Lord Jesus Christ.'