Imagine a child is looking at a wrapped gift sitting under a Christmas tree. It is from an uncle to whom the child is hostile. He looks at the gift suspiciously, and then announces he will not open it. It either holds nothing or else holds something worthless. It certainly couldn’t contain anything that would compensate for being in the uncle’s debt.

So what should a parent say to convince the child to open the present.

• “Oh, if only you will believe, you will receive wonderful grace!”?
• You’ve misjudged your uncle. He loves you. He is quite capable of giving you more than you can ask or think!”

The second option does not even mention words like “trust” or “faith” or “believe” and yet both options call for faith and the first one does so quite lamely.

If you want someone to trust God, then extoll God’s trustworthiness, not the alleged power of faith. “God is faithful,” Paul wrote the Corinthians (First 1.9).

The reason Paul had to speak of faith was because some were denying that all believers were equal in their status before God. Something more than being a believer is required, they said.

Outside of that sort of context, extolling faith can become utterly superstitious (c.f Trinity Broadcasting Network).

Giving the impression that one makes the sacraments efficacious by believing or imagining may be as superstitious than the errors such impressions are designed to prevent. Here’s a better way:

I know it is a common belief that forgiveness, which at our first regeneration we receive by baptism alone, is after baptism procured by means of penitence and the keys (see chap. 19 sec. 17). But those who entertain this fiction err from not considering that the power of the keys, of which they speak, so depends on baptism, that it ought not on any account to be separated from it. The sinner receives forgiveness by the ministry of the Church; in other words, not without the preaching of the gospel. And of what nature is this preaching? That we are washed from our sins by the blood of Christ. And what is the sign and evidence of that washing if it be not baptism? We see, then, that that forgiveness has reference to baptism. This error had its origin in the fictitious sacrament of penance, on which I have already touched. What remains will be said at the proper place. There is no wonder if men who, from the grossness of their minds, are excessively attached to external things, have here also betrayed the defect,óif not contented with the pure institution of God, they have introduced new helps devised by themselves, as if baptism were not itself a sacrament of penance. But if repentance is recommended during the whole of life, the power of baptism ought to have the same extent. Wherefore, there can be no doubt that all the godly may, during the whole course of their lives, whenever they are vexed by a consciousness of their sins, recall the remembrance of their baptism, that they may thereby assure themselves of that sole and perpetual ablution which we have in the blood of Christ (John Calvin, Institutes, IV, 15, 4).Nineteenth Question: The Efficacy of Baptism
Does baptism… take away past and present sins only and leave future sins to repentances? Or does it extend itself to sins committed not only before but also after baptism? The former we deny; the latter we affirm against the Romanists.…

II… [T]he Romansists teach… “The virtue of baptism does not reach to future sins, but the sacrament of penitence is necessary for their expiation.” Thus, the Council of Trent expresses it: “If anyone shall say that all the sins which are committed after baptism are either dismissed or made venial by the recollection of faith of the received baptism alone, let him be anathema (session 7, Canon 10, Schroeder, p. 54)….

XII. …However, we maintain that by baptism is sealed to us the remission not only of past and present, but also of future sins; still so that penitence (not a sacramental work and what they invent, but that which is commanded in the gospel) and especially saving faith is not excluded, but is coordinated with baptism as a divinely constituted means of our salvation (Francis Turretin, Institutes of Elenctic Theology, vol. 3).