I see one guy online, Jack Buckby, criticising Sinead O'Connor for becoming a Muslim. To my mind, that is beyond the pale. Religious faith is private. It is arrogant to assume we know better than another what their walk with God entails.
We do all know O'Connor has had serious struggles with her mental health. She seems to be “bipolar,” to use the standard diagnostic term. This means turning to religion is exactly what she needs to do. But her mental suffering is probably also due to some form of abuse during childhood. And it may well be that her childhood experiences have closed Catholicism to her. That's what can happen if you are abused by a priest, or if an abusive parent uses bogus religion as a club against you. God can start to look like the abusive priest or parent writ large across the sky—when you, the abused, are the one most in need of Him. Bad people will almost always try to co-opt religion for their purposes.
Moving to Islam may therefore be exactly what O'Connor needs. And this need not imply some error in Catholicism.
This may well by why God in his wisdom has allowed more than one religion to flourish. For cultural or for personal reasons, one or the other may work better for each of us. This may be because our upbringing or our culture has poisoned some once sacred well. Christianity itself arose in objection to the abuse of Judaism by the Pharisaic authorities of Jesus's day, who had turned it into a club to lord it over people. Yet this was no comment on Judaism. It does not mean, has never meant, that the convenant with the Jews was invalid, or has ever lapsed.
Religion is not a competition.
Sinead O'Connoer deserves our support and prayers.