If heresy was still a burning offence, it might just be the time to say, 'bring on the flames' and ask whether it is really true that Barcelona are the greatest club team football has ever seen.
Beautifully skilled, of course they are. Marvellously adept in the important matter of hogging possession, there is no doubt. There was still a plentiful supply of these qualities when Milan, a wonderfully vigorous and motivated Milan, delivered the shock of the Champions League season with a 2-0 victory in San Siro this week but there was also that doubt that has, in the most stringent judgment, never been dispelled.
To be the best club team in the history of the game they need irrefutable evidence that they not only have sublime skills but a most superior cutting edge, something to compare with that of the Real Madrid which was quite unassailable in the first five European Cup campaigns.
There are other claimants who have been shuffled off the big stage during the prolonged coronation of Messi's Barca – teams like the Milan of Baresi, Gullit and Van Basten, the Ajax of Cruyff and the Bayern of Beckenbauer and Muller, the Liverpool of Souness and Dalglish.
This week in San Siro such neglected phantoms of the past surely re-appeared.
They came back along with a necessarily more searching look at the record of the Barca team that first announced itself with Champions League victory over Arsenal at the Stade de France in 2006. It is imposing enough, no doubt, with three European titles in six years but there are plenty of reasons to withhold the ultimate praise that they are indeed the best we have ever seen.
The main one is that Barca have simply never imposed themselves in the way of Real – or, when you think about it, the Milan of Fabio Capello which outplayed Johan Cruyff's Barcelona in Athens in 1994 in what some still say was the most devastating performance ever seen in a European final.
Barcelona were strong favourites as Capello went into the game shorn of Baresi, suspended, and with injuries to such key figures as Van Basten, the £13m youngster Lentini and the formidable defender Costacurta. Yet Milan were inventive and ruthless around the goal in the way that Barca have never quite been at such a pinnacle of the game.
Arsenal's currently embattled manager Arsene Wenger still has nightmares over Thierry Henry's critical miss in the Paris game, when the London team were reduced to 10 men after just after 18 minutes but took the lead and stayed in front until 14 minutes from the end. Even then, the 2-1 victory had very little to do with today's Barca, only Victor Valdes and captain Carles Puyol starting. Messi didn't play and Barca's pivotal performer was substitute Henrik Larsson, who was playing his last game for the club.
Three years later, Barca won again, in Rome, outplaying Manchester United, but overall the triumph was hardly among the most imperious the tournament had ever seen. Indeed, Barca had reached the final only after the help of outrageous refereeing in the semi-final second leg at Stamford Bridge. They were seconds away from expulsion – United had stifled them in the semi-final the previous season – when Andres Iniesta drove home the vital away goal. It was Barca's first direct shot on goal.
Two years later, they beat United again, at Wembley, and both Messi and Xavi were immense but then again United were slight by their best standards and the idea that we had seen the greatest side of them all was hard to sustain.
In 2010, Jose Mourinho had parked his Internazionale bus and left Barca in a fever of futility. Last spring Chelsea, though rather more fortuitously, inflicted the same frustration at the Nou Camp. Now the team of the 'Holy Trinity' of Messi, Iniesta and Xavi are threatened with entirely unexpected exclusion from the last eight of the tournament which so many people believed they had come to own.
But of course the briefest examination of their record makes this a somewhat outrageous presumption, an immersion in the moment rather than a balanced view of the full sweep of European football history.
There is one point of inescapable comparison when we consider the most powerful claimants to the mythic title of the best ever team.
It has to be Real's extraordinary triumph in their fifth straight European title game before stunned a 127,000 crowd at Hampden Park in 1960. They beat Eintracht Frankfurt 7-3 and no one in Glasgow needed telling what the feat quite represented. The Germans had beaten Glasgow Rangers in the semi-finals 12-4 on aggregate. Real, ironically enough in the current debate, had swept by Barcelona 6-2.
The Hampden game was quite extraordinary in the quality of the football. The Germans made an impressive contribution before becoming overwhelmed by the sheer virtuosity and firepower of such as Alfredo di Stefano, Ferenc Puskas and Francisco Gento.
Di Stefano scored three, Puskas four and Gento was just about unplayable. A few years earlier, Bobby Charlton had gone to the Bernabeu as the travelling reserve and he watched the game from the stands. In the end his concentration was fixed entirely on the extraordinary Di Stefano.
"I was mesmerised," recalled Charlton. "I thought, 'who is this man?' as he made his early impact on the game. He takes the ball from the goalkeeper; he tells the full-backs what to do; wherever he is on the field he is in position to take the ball; you could see his influence on everything that was happening.
"Whenever he got into any kind of decent position in midfield it was the signal for Gento to fly. He would go at a 100 miles an hour, Di Stefano would send the ball unerringly into his path, Gento would go bang, and you just heard yourself saying, 'Oh my God.'
"It was pure revelation. Everything seemed to radiate from him."
Messi keeps on winning the Ballon D'Or and he is continually bathed in the highest of praise, but then we could only have guessed what he would have given for such a review when wrapped in the iron chains of Milan on Wednesday night.
Of course he has the power to rise again at the Nou Camp, along with his extraordinary team, but in the meantime it is perhaps only fair to remember the strength of just some of the historic opposition.