"There is...no good and bad"

It's a nonsense presentation of a concept that is being twisted by oversimplification but is otherwise a valid observation:

Everything is dual; everything has poles; everything has its pair of opposites; like and unlike are the same; opposites are identical in nature, but different in degree; extremes meet; all truths are but half-truths; all paradoxes may be reconciled.

This is the same principle by which we know, for example, that negative and positive charges are the same concept: electricity.

To draw that back further to a Biblical exegesis because that's ultimately one of the pillars this is built upon:

I form the light, and create darkness: I make peace, and create evil: I the Lord do all these things. (Isaiah 45:7)

For everything there is a season, and a time for every purpose under heaven: ... a time to love, and a time to hate; a time for war, and a time for peace. (Ecclesiastes 3:1,8)

A lot of people always stumble on the "paradox of evil" because they don't understand that at the level of God's Will all things are part of His plan. God's allowance of evil acts within creation is a "relative" polarity within His creation. God's action causes everything to exist and His role is absolute. The "gradient" applies within a time-based existence. Evil is the "lack" or perversion of good. And good is the "abundance." These two poles remain as a gradient of alignment with God's ultimate goals... or just truth. This polarity isn't destroyed by the fact that there's the absolute "unity of opposites" found in God's Will or the understand that goodness is more in tune with God's Will. As is stated by Joseph of his brothers in Genesis 50:20, "As for you, you meant evil against me, but God meant it for good..."

Knowing this, one should still conclude rightly that child abuse is wrong just as murder is wrong or robbery is wrong. The sin is still a sin, that is "a missing of the mark." But the judgment of that sin isn't to be made in a relative capacity where we can't judge fully. That's where the reconciliation of God comes in through His own work of reconciliation. God ultimately chooses how to balance sinful acts with the truth. Either with a righteous Judgment of condemnation for evil or by bringing sinners to repent of their evil and reconcile themselves with God.

Only God can balance any deviations from the absolute principle while maintaining the necessary potential for duality that exists within creation as "imperfect" means are sometimes necessary to accomplish the ultimate good. Men may sin, yet be brought to repentance and saved. And for that we must always leave room for God to work.