The Prayers of Unconverted Covenant Children

Herman Witsius, Sacred Dissertations on the Lord's Prayer, pp. 168-170:

But here another question arises. To speak falsely to God must be heinously wicked, and no prayers which do not proceed from faith can find acceptance with God. Does the right to use this prayer, and to call God his Father, belong exclusively to him who is truly a child of God by regeneration and adoption, and who has been convinced of his sonship by the peculiar influences of the Holy Spirit. I answer -- I. Proper and acceptable prayer can be offered only by a believer and a saint. Every prayer which deserves the name must proceed from the spirit of prayer. But the spirit of prayer is the spirit of regeneration and adoption. Consequently, no man can pray aright who is not a son of God. Because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.3
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III. Those who belong to the external communion of the church, but have not been born again by the Holy Spirit, cannot call God their Father in the same sense as believers. Yet prayer, and other religious duties, are enjoined on these persons. To lay down for a them a different manner of prayer, in which the Divine Being should be viewed as a Creator and Lord, would serve no good purpose. So long as they do not approach God with filial love, all their addresses will be vain. Let them be taught that no one can pray aright who is not a child of God, and that, therefore, they ought earnestly to implore from the Divine Being that high privilege. Let them be further taught that God is truly their Father, and may justly be so designated, in respect of creation, preservation, and a multitude of blessings which he has liberally bestowed upon us; but that nothing short of his being their father by regeneration and adoption, will promote their real happiness. Let them, therefore, call God Father, as far as they are able to do so, still aspiring to that grace by which they may be enabled, in the strongest sense of the expressions, to claim him as their own. Beyond this point the question may be safely dismissed, as it can only perplex the exercise of prayer by curious distinctions and excessive refinements, on which the Divine Being will not bestow his approbation.

3 Gal. iv. 6.