The enemy comes to steal and destroy you and all that is good. He is real. This is where he starts. Your heart. If he can change your heart. He will change you.

Jeremiah 17:1-10 AMP

THE SIN of Judah is written with a pen or stylus of iron and with the point of a diamond; it is engraved on the
tablets of their hearts and on the horns of their altars, While their children [earnestly] remember their [heathen]
altars and their Asherim [wooden symbols of the goddess Asherah] beside the green
trees upon the high hills. O [Jerusalem] My mountain in the field, I will give your
wealth and all your treasures to the spoil and your high
places for sin [as the price of your sin] throughout all your territory. And you, through your own fault, will loosen your hand and discontinue from your heritage which I gave you; and I
will cause you to serve your enemies in a land which you do not know, for you have
kindled a fire in My anger which will burn throughout the ages. Thus says the Lord: Cursed [with great evil] is the strong man
who trusts in and relies on frail man, making weak [human]
flesh his arm, and whose mind and heart turn aside from the
Lord. For he shall be like a shrub or a
person naked and destitute in the desert; and he shall not see any good come, but
shall dwell in the parched places in the wilderness, in an uninhabited salt
land. [Most] blessed is the man who believes in, trusts in, and relies on the Lord, and whose hope and confidence the Lord is. For he shall be like a tree planted by the waters that spreads
out its roots by the river; and it shall not see and fear
when heat comes; but its leaf shall be green. It shall not be anxious and full of care in the year of drought, nor shall it cease
yielding fruit. The heart is deceitful above all things, and it is exceedingly
perverse and corrupt and severely, mortally sick! Who can
know it [perceive, understand, be acquainted with his own heart and mind]? I the Lord search the mind, I try the heart, even to give to
every man according to his ways, according to the fruit of his doings.

Proverbs 4:23

This is the key to everything. It is the temple of the almighty and my creator. My heart should be the dwelling place of the Holy Spirit.

Psalm 119:11 NLT

I have hidden your word in my heart, that I might not sin against you.

Lord all though my memory is not good. You have helped me to hide your word in my heart . Thank you. Holy Spirit!