the prayers of heretics are abominations

"This is the glory, the joy, and assurance of a Catholic man, that Jesus Christ is in him the chief agent, the which for his reverence is heard of God in him: and this is the true firmament of the Catholics, more firm than heaven itself. It is not so in heretics, all that which of heretics is accursed and [an] abomination before God: their faith, their preaching, their prayers, their fasting, their alms, all acts of Religion coming from them are nothing else, but cursed sacrilege and pollution. If they should raise up the dead, if they should be more wise than Angels, if they should have their faith as great as to move mountains, if they should distribute all their goods to the cherishing of the poor, if they should keep heroically continual virginity, if they should sing with an Angelical holiness, all this serveth them for nothing, being divided from the body of the Church: All this would not anything appease of the rigour of the eternal ire of God upon them."

"Core, Dathan, and Abiron did sacrifice to the same God that Moses did, yea to the only true and almighty God, but for it was done in division from the body of the Church, the earth did open and swallow them up alive..."

from The Firme Foundation of the Catholic Religion by Jean de Caumont