These the Lord kept for the purpose of testing all who had had no experience of all his deliverances

Faith is tested as by fire

Now these are the nations which the Lord kept in the land for the purpose of testing Israel by them, all those who had had no experience of all the wars of Canaan;
Judges 3:1

1)1Pe 4:12 Dear brothers, do not be surprised, as if it was something strange, if your faith is tested as by fire

Jdg 3:2 Only because of the generations of the children of Israel, for the purpose of teaching them war–only those who up till then had no experience of it; 2)Eph 6:11 Take up God’s instruments of war, so that you may be able to keep your position against all the deceits of the Evil One.
Eph 6:12 For our fight is not against flesh and blood, but against authorities and powers, against the world-rulers of this dark night, against the spirits of evil in the heavens.
Eph 6:13 For this reason take up all the arms of God, so that you may be able to be strong in the evil day, and, having done all, to keep your place.
Eph 6:14 Take your place, then, having your body clothed with the true word, and having put on the breastplate of righteousness;
Eph 6:15 Be ready with the good news of peace as shoes on your feet;
Eph 6:16 And most of all, using faith as a cover to keep off all the flaming arrows of the Evil One.
Eph 6:17 And take salvation for your head-dress and the sword of the Spirit, which is the word of God:
Eph 6:18 With prayers and deep desires, making requests at all times in the Spirit, and keeping watch, with strong purpose, in prayer for all the saints,
Eph 6:19 And for me, that words may be given to me in the opening of my mouth, to make clear without fear the secret of the good news,
Eph 6:20 For which I am a representative in chains, and that I may say without fear the things which it is right for me to say.

Jdg 3:4 For the purpose of testing Israel by them, to see if they would give ear to the orders of the Lord, which he had given to their fathers by the hand of Moses.

Jdg 3:9 And when the children of Israel made prayer to the Lord, he gave them a saviour, Othniel, the son of Kenaz, Caleb’s younger brother.

Jdg 3:15 Then when the children of Israel made prayer to the Lord, he gave them a saviour, Ehud, the son of Gera, the Benjamite, a left-handed man; and the children of Israel sent an offering by him to Eglon, king of Moab.

References
11Pe 4:12 Dear brothers, do not be surprised, as if it was something strange, if your faith is tested as by fire
2Eph 6:11 Take up God’s instruments of war, so that you may be able to keep your position against all the deceits of the Evil One.
Eph 6:12 For our fight is not against flesh and blood, but against authorities and powers, against the world-rulers of this dark night, against the spirits of evil in the heavens.
Eph 6:13 For this reason take up all the arms of God, so that you may be able to be strong in the evil day, and, having done all, to keep your place.
Eph 6:14 Take your place, then, having your body clothed with the true word, and having put on the breastplate of righteousness;
Eph 6:15 Be ready with the good news of peace as shoes on your feet;
Eph 6:16 And most of all, using faith as a cover to keep off all the flaming arrows of the Evil One.
Eph 6:17 And take salvation for your head-dress and the sword of the Spirit, which is the word of God:
Eph 6:18 With prayers and deep desires, making requests at all times in the Spirit, and keeping watch, with strong purpose, in prayer for all the saints,
Eph 6:19 And for me, that words may be given to me in the opening of my mouth, to make clear without fear the secret of the good news,
Eph 6:20 For which I am a representative in chains, and that I may say without fear the things which it is right for me to say.