'Solid' in the Bible

For even though I am absent [from you] in body, nevertheless I am with you in spirit, delighted to see your good discipline [as you stand shoulder to shoulder and form a solid front] and to see the stability of your faith in Christ [your steadfast reliance on Him and your unwavering confidence in His power, wisdom, and goodness].

Such things are only a shadow of what is to come and they have only symbolic value; but the substance [the reality of what is foreshadowed] belongs to Christ.