"When someone is playing at the level Michael Vick is playing, you have to give him an opportunity," Reid said. "This isn't about Kevin Kolb's play. You're talking about Michael Vick as one the best quarterbacks in the NFL right now."
Kolb missed the last six quarters because of a concussion, and Vick played well in his absence. Kolb was cleared to practice and was expected to run the first-team offense on Wednesday.
"Kevin is fine. It's not an injury-related issue," Reid said. "It's not about judging him. He's going to be a championship-caliber quarterback."
This decision to go with Vick had been in the works for two days.
Team sources told ESPN's Sal Paolantonio that in the early-morning hours on Monday, Reid, general manager Howie Roseman and the rest of the Eagles coaching staff and front office started going through the game film of Sunday's win in Detroit and saw the severity of the problems facing the Eagles offensive line.
The film study showed that Vick, who was sacked six times, was under constant duress because backup center Mike McGlynn had difficulty recognizing blitzes and then setting the protection. As a whole, the offensive line did not play well, and Reid realized then that Vick, with his mobility, would be a better fit to start rather than Kolb.
There also was a concern that the offensive line's play was so poor that Kolb would be exposed to another concussion, sources told Paolantonio.
As Reid said, Vick is playing "out of his mind right now" and with Donovan McNabb returning to Philadelphia with the Washington Redskins in Week 4, the Eagles believe Vick gives the team the best chance to win.
"I'm humbled and I just want to win games," Vick told Paolantonio via text message. Vick is scheduled to speak at a news conference later Wednesday.
Interestingly, Reid was never specifically asked at his Monday afternoon media session if Kolb would be the starter in Week 3. And he never said so. Reid merely said Kolb was cleared to practice.
"We'll just see how it all works out," Reid said Monday. "I'm not here to justify one over the other."
As it turns out, the decision to stay with Vick as the starter was already in the works. Reid admitted as much on Tuesday night, saying the decision was a "two-day process" and that he made it in consultation with Roseman.
It's hard to say how much Reid was pushed into this decision by the front office, but team sources clearly indicated to Paolantonio that Reid wanted to go back to Kolb -- he is loyal to a fault -- and had to be persuaded to give Vick another look.
"Michael did an exceptional job and my job is to evaluate the players," Reid said. "It's my obligation to make the proper decision."
Vick threw for 175 yards and one touchdown and ran for 103 yards in relief of Kolb in a 27-20 season-opening loss to Green Bay. He had 284 yards passing and two TDs in Sunday's win over Detroit.
Kolb started two games in his first three seasons before he became the team's No. 1 quarterback after McNabb was traded to Washington. Kolb struggled in the first half against the Packers in the season opener.
Vick's start against the Lions was his first in nearly four years. A three-time Pro Bowl pick during six seasons with the Falcons, Vick missed two seasons while serving an 18-month sentence in federal prison for his role in a dogfighting operation. He signed a two-year contract with the Eagles before last season, then played sparingly behind McNabb and Kolb.
Vick has completed 63.8 percent of his passes and has posted consecutive games with a passer rating above 100 for only the second time in his career.
"His accelerated play was brilliant," Reid said. "This is what I think is right. He's back and maybe even a little better."
Information from ESPN NFL reporter Sal Paolantonio and The Associated Press was used in this report.