the geneva catechism 4
246. You do not, however, mean that the tongue is quite useless in prayer? Not at all, for sometimes it helps the mind, sustaining and keeping it from being drawn away from God so easily. Besides, since more than all the other members it was formed to the glory of God, it is very reasonable that it should be employed by all means for this purpose. Moreover, the zeal of the heart by its own ardour and vehemence often constrains the tongue to speak quite spontaneously.
247. If so, what about prayer in an unknown tongue? It is a mockery of God, and a perverse hypocrisy (1 Cor. 14:14).
248. But when we pray to God, is it a venture in which we do not know whether we will succeed or not? Or ought we to be certain that our praying will be heard? The ground of our prayers should always be, that they will received by God, and that we shall obtain what we request as far is it is expedient for us. And therefore St. Paul says that true prayer comes from faith (Rom. 10:14). For if we have no reliance upon the goodness of God, it will be impossible for us to call upon Him in truth.
249. And what of those who doubt, not knowing if God hears or not? Their prayers are utterly void, since they have no promise, for He says that whatever we ask, believing, we shall receive (Matt. 21:22; Mark 11:24).
250. It remains to learn how and in whose name we can have the boldness to present ourselves before God, seeing that we are so unworthy in ourselves. First we have promises on which we must rest, without considering our worthiness (Ps. 50:15; 91:3; 145:18; Isa. 30:15; 65:24; Jer. 29:12; Joel 3:5). Secondly, if we are children of God, He induces and urges us by His Holy Spirit to betake ourselves to Him familiarly, as to our Father (Matt. 9:2, 22; etc.). And lest we, who are poor worms of the earth, and miserable sinners, should be afraid to appear before His glorious majesty, He gives us our Lord Jesus Christ as a Mediator (I Tim. 2:5; Heb. 4:16; I John 2:1), that through Him we may have access and have no doubt of finding grace.
251. Do you understand that we are to call upon God only, in the Name of Jesus Christ?