Rather than bore you with my prose, I leave you some quotations from Calvin:
Mingled vanity and pride appear in this, that when miserable men do seek after God, instead of ascending higher than themselves as they ought to do, they measure him by their own carnal stupidity, and neglecting solid inquiry, fly off to indulge their curiosity in vain speculation. Hence, they do not conceive of him in the character in which he is manifested, but imagine him to be whatever their own rashness has devised. This abyss standing open, they cannot move one footstep without rushing headlong to destruction. With such an idea of God, nothing which they may attempt to offer in the way of worship or obedience can have any value in his sight, because it is not him they worship, but, instead of him, the dream and figment of their own heart.-John Calvin, Institutes, Book I. Ch. 4. Section 1.
In this way, the vain pretext which many employ to clothe their superstition is overthrown. They deem it enough that they have some kind of zeal for religion, how preposterous soever it may be, not observing that true religion must be conformable to the will of God as its unerring standard; that he can never deny himself, and is no specter or phantom, to be metamorphosed at each individual’s caprice. It is easy to see how superstition, with its false glosses, mocks God, while it tries to please him. Usually fastening merely on things on which he has declared he sets no value, it either contemptuously overlooks, or even undisguisedly rejects, the things which he expressly enjoins, or in which we are assured that he takes pleasure. Those, therefore, who set up a fictitious worship, merely worship and adore their own delirious fancies; indeed, they would never dare so to trifle with God, had they not previously fashioned him after their own childish conceits. -John Calvin, Institutes, Book I. Ch. 4., Section. 3.
Hence we must hold, that whosoever adulterates pure religion (and this must be the case with all who cling to their own views), make a departure from the one God. No doubt, they will allege that they have a different intention; but it is of little consequence what they intend or persuade themselves to believe, since the Holy Spirit pronounces all to be apostates, who, in the blindness of their minds, substitute demons in the place of God. -John Calvin, Institutes, Book I., Ch. 5. Section 13a.
Among the gentiles in the time of Christ, the Samaritans undoubtedly made the nearest approach to true piety; yet we hear from his own mouth that they worshiped they knew not what (John 4:22); whence it follows that they were deluded by vain errors. In short, though all did not give way to gross vice, or rush headlong into open idolatry, there was no pure and authentic religion founded merely on common belief. A few individuals may not have gone all insane lengths with vulgar; still Paul’s declaration remains true, that the wisdom of God was not apprehended by the princes of this world (1 Cor. 2:8). But if the most distinguished wandered in darkness, what shall we say of the refuse? No wonder, therefore, that all worship of man’s device is repudiated by the Holy Spirit as degenerate. Any opinion which man can form in heavenly mysteries, thought it may not beget a long train of errors, is still the parent of error. -John Calvin, Institutes, Book I. Ch. 5. Section 13b.
Yep. Smart fella, that Calvin.