Consequently, in order that we may then give a definite form and good directions from God’s Word as to how and in what manner one may and should train oneself in godliness, the treatise of these five books now springs forth. Prior liber erit νουθετητικός, continens pietatis ὀρμητήρια [Vol. I will be admonitory, containing incentive for godliness]. Posteriores erunt διδακαλικός, exponentes pietatis ἐργαστήρια [The latter will be didactic, and will do the work of explaining godliness]. Prior demonstrabit τὸ ὅτι καὶ τὸ διότι, quod & quare pietatis sit studendum (Vol. I will show the why and the wherefore one must pursue godliness); posteriores exponent τὸ πῶς qua ratione pietatis exercitationi incumbendum (the rest of the volumes will explain the whole reason why the exercise of godliness is incumbent upon us).
Both are required for the true practice of godliness. For on account of the corruption of our nature, we are altogether reluctant and lazy regarding godliness; and our hearts flatter themselves with the belief that they are capable of evoking the highest motives which would awaken and encourage us to godliness, as well. Since we especially also, through this very same corruption of our nature, have our spiritual understanding blindly deluded in such way that we do not know how and in what manner we are to serve God, and are unable to train ourselves in godliness, from the Word of God one has to simultaneously defend against the corruption, and search for counsel and help for this sickness of the soul. We want to initiate a beginning concerning the reasons why we should be motivated to godliness. Thus, we thereafter will be all the more willing and eager to be motivated towards godliness if we consider how and in what manner we should and can train ourselves in godliness. GOD wants to grant us His Spirit’s grace and power for the sake of Christ, so that it may redound to His glory and for the furtherance of the salvation of many. Amen. (Schola Pietatus-Volume 1 by Johann Gerhard, Repristination Press, p. 28-29)

Inasmuch, then, as the true believers are also not just simply and primarily here to see a reward in this life, but rather for the promise of eternal life and along with that, are to commend to God the Lord how He may desire to deal with them in this life, whether He wants to lead them to heaven via roses or via thorns, whether He wants to give them cross and adversity or relief from tribulation… all this they are to willingly receive from His hand and in all things, obediently commend themselves into His gracious, fatherly hand.

This is also the Scriptural explanation given to Timothy by this apostolic rule: Train yourself in godliness, that is serium pietatis studium [the serious pursuit of godliness]. For bodily training is of little value, but godliness is good for everything and has the promise of this and the future life, that is amplissimum pietatis proemium [the farthest reaching reward for godliness].

By relying on divine help, let us and others, by responsibly following this apostolic rule, train ourselves for godliness. [Let us do it] in such a manner that we, at the beginning, search out the most important and moving reasons which should, in general, encourage and awaken each individual to godliness, which yet not everyone makes their top priority. Let us sharpen these skills. (Schola Pietatus-Volume 1 by Johann Gerhard, Repristination Press, p. 28)

Second, as we consider this benefit of godliness is the matter that by the promise of this life is understood to mean the reward in this life cum exceptione crucis & salutis [with the exception of the cross and salvation]. With this is indicated that it will not redound to our salvation and be of benefit to us that God the Lord, in this life, lays upon us the fatherly chastisement of crosses. Christ teaches us this in Mark 10:29–30: Anyone who forsakes house or brother or sister or father or mother or wife or children or land for My sake, and for the sake of the Gospel, will in this present time, receive a hundred-fold of houses and brothers and sisters and mothers and children and land amidst persecution; and in the future world, eternal life. Here, we clearly hear that the promise of this life or the reward of godliness in this life, takes place amidst persecution; that is to say, this will not occur apart from cross and adversity, for all who desire to live godly in Christ Jesus will have to suffer persecution (2 Tim. 3:12). My child, if you wish to be a servant of God, then prepare yourself for anxiety (Sir. 2:1). Since you love God, it has to be that you will not remain without anxiety, in order that you be preserved (Tob. 12:13).
It would be very easy for God to richly grant the godly everything good in this life; for Him to give them relief from all anxiety, tribulation and adversity; along with this, to give them riches, honor, health and all blessings. However, He knows very well that the godly still bear flesh and blood within them, which so very easily could abuse all of this and bring upon itself eternal retaliation. That’s why He keeps them under the cross in this life and, at the same time, He does good things for them in the midst of cross and tribulation, in that, through the Holy Spirit, He mightily comforts and strengthens them, assures them of His grace, makes them to be happy and confident that they with David may say, from Psalm 119:71: I love that You have humbled me—understand, by means of cross and adversity—so that I may learn of Your righteousness. (Schola Pietatus-Volume 1 by Johann Gerhard, Repristination Press, p. 26-27)